Were there any particular pieces of classic science fiction that inspired Wool, or at least the world it was set in?
The biggest influence on me was probably Fraggle Rock. As a kid, I couldn't get enough of the intro to that show, which revealed an entire world underground. As for sf literature, the Foundation series introduced psychology as a driving force behind the actions of people for generation after generation, and that was a huge influence. The writing style of Herbert and Asimov rubbed off on me as well. Just not enough, I'm afraid!