I have an Affinity frame, and like it a lot, but I've never been to their shop. Might as well go check it out. Fixed gear bikes are much more popular now than they were several years ago, so even a shop that doesn't specialize in them will probably have some options for you to check out. I can't recommend a particular book, but I do recommend you google the name Sheldon Brown and read as much of his site as you can.