As for normal interpolation you have to be able to export smoothing groups, for that the fbx format works decently. The ase format instead doesn't export smoothing groups at all and turns the whole mesh into a 1 big smoothing group.
But it's not that easy to get the desired results anyway, you wanna keep your geometry as much simple as possible, and keep an eye on your triangulations flow.
Infact this is exactly why you're not seeing me posting any new screenshots, I had to start from nearly the beginning, remodifing all my meshes and re-exporting them all.
For example if I had to apply a window to a house, I wouldn't extrude it internally cutting through the wall adding polygons, but I would create it externally as another detached mesh and placed it close the wall. That way your wall is a quad.
