Lothlórien

So, lets look at the threats that the Lothlorien government has to contend with.
If we assume that Moria that gets reestablished, it would become a threat in terms of its numbers and location. But the dwarves would suffer from a severe military problem - the formations it uses would be impractical. The fortifications and natural terrain combined with the elven fighting style would mean that the dwarves would be weak against the elves in their natural environment. Not to say that the dwarves would suck, but army of Lothlorien would be perfectly set up to counter an invasion from Moria.
Moria though is much less threatening when you look at incentives. Moria does not directly threaten any vital interests. It might need fuel to feed its industries, but that can be gained from the other side of the Misty Mountains and slave labor to provide coal. Secondly, the economic prosperity of Lothlorien is what would be primarily affected. As this is a secondary state priority, Lothlorien would be more open to talks to resolve differences. But we have to recognize that like the elves, the dwarves suffer from population decline. The result is they would be a receding threat. They also would represent a national threat. Moria would be more of an economic threat, but would probably not attack in any political or military ways. In this sense it is likely to be the only threat that takes an unconventional and non lethal approach. All the other ones would likely us normal war tactics to kill their way to victory.
Isengard also has numbers on its side in a battle with Lothlorien. It would have more troops and appears to have a stronger emphasis on combined arms tactics. Again though the terrain and elven infantry would be perfect against an invasion by Isengard. But it can replace losses a lot easier than Moria and is much less concerned with attrition. Which gives Isengard an advantage. Should Isengard exploit its willingness to commit atrocities to its advantage, Isengard can overcome Lothlorien's doctrine via scorched earth tactics. This would allow them to more easily force Lothlorien into the sort of pitched battle that Isengard would have an advantage in. Isengard would also be a political threat due to its use of subversion in addition to its obvious military posture. It is unlikely to try and use and economic means though.
Isengard appears to be a direct threat to Lothlorien on all three fixed priorities. It uses subversion to break the enemy. The homes of the elves would be the raw materials that Isengard would be after. Nor could Isengard accept the existence of a hostile population skilled in guerrilla warfare. More importantly, I do not see how Isengard cannot turn Lothlorien into his next target after Rohan. They are clearly going to be hostile to Saruman's environmental destruction and have more of the sort of resources he needs. Lothlorien needs to fall to make sure that Isengard gets the sort of resource and territorial security it clearly lacks. In this sense Isengard is a high intensity, national, short term regional threat. Isengard is also an expanding threat. Each victory will lead to an increase in his power and thus threat status. Saruman is interesting in the sense he does not actually want to destroy the international system. Just so happens that the means he chose are contradictory to his ends.
Easterlings must also be factored in as well. They too have numbers on their side. But the Roman style marching and heavy infantry based legions means that they are exactly the sort of enemy the elves would be masters at defeating. Like the dwarves, the easterlings would struggle against an enemy even though they are competent fighters. Easterlings would be a threat purely to the territorial integrity of Lothlorien. The internal stability or survival of its people would not be directly threatened by the Easterlings. However, they do not have any real incentive or history of striking against Elves.
In fact, I doubt they would have any plan to unless Sauron gives them the order. He certainly would though if his army is not in a good position to attack. They would be more of a long term and expanding threat in the sense that their ideology and economic policies require constant expansion in order to survive. In this sense they are also a global threat. But in the short term, not really unless Mordor orders the attack. Which means they would be more regionally focused - only on defeating Lothlorien and not any real global coalition. But when that attack materializes, in whatever form it takes, it is likely to just be military. After all, such militaristic cultures would disdain a victory obtained via any other means.
Mordor is clearly a threat. Unlike the rest of the foes so far, would not be a threat due to the quality of the troops in any way. Instead, huge numbers of troops and a willingness to accept huge losses would turn attrition into an ally. We can assume that Sauron is a threat to the territorial integrity and survival of Lothlorien. Sauron also has a long history of war against elves and atrocities against them. They have proven that they have the means and will to stand in his way of global conquest. And Sauron's power is likely to continue to expand the longer he goes unopposed by a rival superpower.
Mordor would be a long term, global and high intensity threat. It would clearly represent such a severe problem that there is no option but to mobilize all resources to defeat it. And it will continue to threaten Lothlorien and the entire world and the international order until that happens. But Mordor is unique in this regard. The One Ring literally is the only thing keeping Lothlorien alive. When it was destroyed, the magic that sustains it began to fade so fast that 120 years later it was gone. But so long as the One Ring exists, Mordor will continue to attack and threaten every thing. Lothlorien is in a no win scenario with regards to Mordor.
Essentially, all the other states are not in a position to attack. Gondor and Rohan have no motive. Rohan is too weak. The Lonely Mountain is too far. Corsairs and Southrons also can't get there and don't have the needed military might. Fangorn has a history of cooperation and cultural friendship. Just like Gondor, Rivendell, Mirkwood, Rohan and Moria. Also, many of the states aligned to the Free People would have fundamental interests (like Gondor) that require alliances with it. Essentially the international forces at play for places like Rohan, Gondor, Moria, the Lonely Mountain and Mirkwood all make alliances far more of a sound way to secure their vital interests. So a lot of the Free People have the option to strike. But they either have no incentive to attack or an incentive to actively seek alliances.

Demographics

The residents of the forest were Silvan elves. They spoke a dialect of Sindarin so divergent from the main language that Frodo was unable to understand the elves here. The Galadhrim also apparently spoke little of the common language of Middle Earth. So we can assume they are pretty isolated in Lothorien.
When Eregion was destroyed, many of the refugees fled through Moria to safety. These elves came to be the first settlers in Lothlorien. Others came to found Rivendell. We can assume then that they would not be too hostile to dwarves due to this.

Government

Galadriel and Celeborn were the Lord and Lady of Lothlorien. Celeborn was Sindarin and originally the ruler of Lidon in the second age. After Galadriel left, he ruled Lothlorien alone. He, with Galadriel were the ones who introduced Mallorn trees to the forest. So they were not the first, but certainly the most important rulers.
But we have to admit that Galadriel is the dominant force of the couple. She is the one who is in the White Council and has the Ring of Power. The fact that she was a Noldor Elf replicates a pattern expressed elsewhere - Noldorians forming the elites of a society of Sindarin elves. Meanwhile, Galadriel herself was one of if not the oldest, wisest of the elves even by Noldorian standards. Many of her magical abilities and skills came from her extensive contact with various valar and maia spirits related to crafting and plant life. It is said that the combination of these effects means that only Sauron with the One Ring is strong enough to take Lorien. In fact, three attacks were made and each failed. Galadriel even launched the attack that destroyed Dol Guldur, eliminating a powerful base of operations for Mordor in the process.
Now, there is a major family connection binding the elven realms and Gondor together. Elrond married Galadriel and Celeborn's daughter. This then makes them the grandfather of Arwen - Aragorn's future wife.

Defences

Also interesting are the defenses. This is the only city in Middle Earth I am aware of with a moat. Granted, it is a dry moat, but those did exist in real life and the forest would probably break up attacking armies enough that the builders felt the water was not needed. The other was the walls. While most defensive walls in Middle Earth are stone, the ones here in Lorien are earthworks.
Also important is the location near the intersection of two major rivers. Now, these are described as actually making it easier to invade, but I do not see how this is possible. One of them - the Anduin - is rather wide, has cliffs on its banks in some areas, plus waterfalls and rapids. I wonder how exactly this is supposed to help an attacker. Any river would slow down invaders as it is harder to wade than it is walk on dry land. Then add in the fact that they would probably need boats and the problems expand. Essentially, these rivers should actually make the enemy a sitting target for the archery based elves who can fortify and conceal solid positions to fire from inside a forest. This forest would make it much harder after crossing to reform line infantry formations, which then compounds the issues.
There was large amounts of forest outside of these defenses, with guardhouses along the perimeter. Though its greatest protection was the fact Galadriel had a ring of power that prevented decay of the forest environment, as well as a spell warding off creatures with evil intent. If we remember, Nenya's powers provide a boost to concealment. It is also from here that the Fellowship gets their invisibility cloaks. This suggests to me that Lothlorien would rely more on ambushes, sniping and other stealth based tactics more so than the rest of the elves.
Now, their location and military power made it a center point for elven resistance to Mordor. And in the movies Isengard. Only Lothlorien was in a solid position to get troops to Helm's Deep in time to help. This fits well with the Elven idea of having other powers step up and bearing the brunt of enemy attacks. Only with the troops from Lothlorien was Rohan able to withstand Isengard long enough for Gandalf to show up. Which meant that Isengard's army never made it to Lothlorien. Even with all the elves at Helm's Deep dying, their losses were still much less than if that same army directly attacked Lothlorien.

Infrastructure

The location of Caras Galadhon at the intersection of two major rivers was a great aid in international communications and trade.
Stairways and ladders were used to get up to the different houses built in the trees. There appears to be at least one major ground level road. It circled the outside of Caras Galadhon then entered the city through its southern (and only) gate. Lighting was mainly from lamps that produced green, gold and silver light.

History

Lothlorien was the strongest of the Elven Kingdoms at the time of the War of the Ring. So it took the lead in banishing Sauron from Dol Guldur. Later, it was attacked three separate times during the War of the Ring. Each failed, but large sections of the north and east closest to Dol Guldur did take a lot of damage. To a lesser degree the western section was hit by orcs from Moria. When Sauron was finally defeated, Lothlorien again attacked Dol Guldur, finally eliminating Mordor's forces from the area once and for all.
But that was its last gasp. The One Ring's destruction meant Galadriels' Ring was less effective. She, like many of its residents, left for the Undying Lands. Arwen came here to die after Aragorn's death. By that point, it was virtually deserted and in ruins.

Architecture

Lothlorien is seen as the best example of the conservation/preservation based aesthetic of the elves. I would imagine this would be most clearly represented in their buildings.
The main buildings in Lothlorien were tree houses called flets. These ranged from quite simple to the grand. I have little to work with on how the elves built theirs, but modern tree houses can provide some guesses. The first is using the branches as load bearing foundations for the floors. Stilts can be used to help reduce the loads on the trees themselves. To avoid the need for screws or nails to attach the platforms, I would suspect tha tension and friction based fasteners to be used. Ropes would be useful for this, especially given the quality of elven rope. But I also think this would be temporary. Vines can be theoretically be used for the same purpose and would fit the Elven aesthetic better.
The comments I have found describe the buildings as mainly open platforms. Ladders grant access via a hole in the center. Light screens were used to block the wind.
One of the biggest was on Cerin Amroth. This was a huge artificial mount around which two rings of Mallor Trees were planted. The result would be a rather impressive residence taking a rather important position. It was also used as an outlook position. But such a hill would also use useful as a refuge position. I would not be surprised if in real life, the Lothlorien elves would retreat here and have it more fortified than the rest of the area. We can also assume that because of this, the wider Caras Galadhon city would function as a form of motte and bailey modified to fit within the elven fortifications I describe in that article.
The city of Caras Galadhon was a circle 3,000 feet across. This entire area appears to be mostly the mallorn trees. The largest one in the center has the Chamber of Celeborn on it, where the Lord and Lady of Lothlorien reside.

Geography

So, the general area is described as a broad, woodland valley. But what makes Lothlorien interesting is that it is not surrounded by a forest but built into it with its residents living in the trees. The city itself is on a hill covered in huge Mallorn trees, which the Atlas suggests are close to the size of California redwoods.
To the west was the Misty Mountains, with Moria being quite close. The river Anduin formed the eastern side. Across this river was the part of Mirkwood that Dol Guldur was in. Most of the realm was north of the Silverlode river. The main city of Lothlorien, Caras Galadhon, was located 10 miles from where these two rivers meet.

Natural Resources

Due to the effects of Galadriel's Ring, the forest is in a state of never ending spring. So we can assume that fruits and berries would be the primary food. But forests are not typically great for crops like wheat or potatoes. So traditional agriculture would not be a strong suit for Lothlorien given its environment.
The Mallorn trees are the main unique natural feature of Lothlorien. The bark is smooth and silver colored. The branching is described as similar to beech trees. The top of the leaves are pale green but silver on the bottom. But they do not fall in the autumn - instead turning a gold color that makes them appear to glisten in the sun. The flowers were similar to cherry that produced a silver nut. When the flowers open, the automatically drop their leaves, coating the ground with gold. The affect is the floor and canopy of Lothlorien appears gold and silver columns holding up the whole community. While the Lothlorien Mallorn trees were not the biggest in Middle Earth, they were still massive.
Its trees also provide a lot of protection against the weather due to their size and not losing their leaves. This then aids in defense from the air. The Fell Beasts the Ring Wraiths use make them great at aerial observation, but these leave block that. The ability to use air power to burn areas technically can happen if we assume that Greek Fire or some of Isengard's technology is available to Mordor. But I have yet to find evidence that those options are available. Which means there is no counter for this advantage.
It is also possible that there are Huorns in Lothlorien, but I could not find confirmation of this. At first, Fanghorn and Lothlorien were part of one massive forest. Only deforestation came to separate them. Which means that the climate would be right for them to be in Lothlorien too. There was also an agreement With Treebeard that allows residents to cross freely between the two realms.

Population

There are comments that suggest several thousand residents. But no real numbers.

Inhabitant Demonym

Galadhrim, literally "tree-folk"