1. It's almost certain that the speed increase you'd get from intentionally merging a lot of source files into one is less than what you could achieve with a more intelligent profile-based refactoring approach. I wouldn't have a very high opinion of the approach you describe, not knowing any more about those libraries or their authors' motivations.

2. Read a lot of C code written by people like Sean Barrett. You would just pick up a lot of bad habits from mine. :)