there is no missing textures, the problem is some meshes appear in a different place, one wall is displaced if you can see.
I dont know what you mean by 'hirerachy', i didn't set any hirerachy in the map, furthermore, some objects are where they are supposed to be.
No, i don't think mixing everything in a single object is a good idea, uv mapping would be almost imposible
I don't wanna ask nico, he's probably busy ^.^
Not yet.