I think it'd be more useful for me to make a little pack of guide models, like just cubes but at the right scale for floors and walls, it would mean that as long as you don't scale you could use it as a template. I'll see if I can get that posted tonight.
-What size/scale should be used to create segments (walls,floors)?
TBA
-What is the polygon limit?
You should keep it as low as you possibly can, how smooth things run will depend on how greedy you've been with details.
-What is the exporting method to use? (assuming .x file, but what options?)
I'd export to .3DS then export from the DBC 3DS to .X converter, works fine for me.
-What are the texture size limits?
The texture res can be specified when building the game, I'd stick to 512x512 and worry about it later.
-can smoothing groups be used?
Yep.
-can multiple textures be used?
Yep, but not on single meshes right now.
The entities and segments use a very similar system. Inside the editor you can change textures, so it should be straightforward to have different textures for the same mesh.
Van-B
It's c**p being the only coder in the village.