Quite a bit of those pieces could share the same texture, the look to be pretty much identical, just flipped or stretched? It depends on how much you plan on mixing and matching the pieces if you'll really want to unwrap them all separately and give them unique textures. Personally I think you have broken things up too…
Vig's got some good answers. To be fair to you, I personally think building modularity is quite a complex subject to tackle. Especially because there are so many ways to do it. So don't feel bad about asking questions. It's a great way to learn! Look for your building specs and texture sizes and then create it the way YOU…