AAS doesn't support meshes, only brushes.
Animation works fine on mesh-based terrains.
There are no bots in Doom 3, but AI navigates using AAS (although it can navigate without AAS, it's better to have AAS).
In Doom 3 mesh based terrain is what you want. You could do brushes, but it's a pain in the ass. Plus performance will suffer if you have crap load of brushes.
Bezier patch surfaces will never give you good terrain.