Excellent point about the planning THW. From what I've read of some human cultures even let alone fantasy ones there are plenty of places that even if your poor planning collapses your home or a neighbors that's just the way of things and no government or higher degree of planning may be present. Perhaps my thinking was overly tainted by the traditional view of orderly dwarves.

Food source has always been an interesting one to me in particular. Ultimately (with the exception of geothermal vents which would be a fun option to explore) the sun provides the energy for all ecosystems. The only large influx of outside nutrients I can see coming into a cave system (unless you create one like underground migration routes for some large land animal, another fun option) is that which can be carried by an underground river. So fishing would be important. From several accounts I've read villages tend to poison their own creeks once they grow too big which causes a die off of the fish. With a big enough river you can't put enough waste in it as easily, so you'll need a large underground river. If you are going to do the fungus, as you point out, you'll need food for fungus. You could maybe modify a system with bat's bringing in enough of the right kind of waste (the actual guano is pretty nasty stuff though mixed with other things is some killer fertilizer) or some other imaginary animal. In some ways though this problem is common to all large cities none of which can produce enough food without outlying lands.

As far as temperature goes, it might not be warm, but it is very constant and there is no real change in season or the like so if your body as well as culture developed there you are living the easy life as far as adaptation. This seems like it would also have an effect on buildings as what weather is there really to keep out?