"Government Information" (yes, I know I need help, many people have told me so, lol)
Our textbook was
United States Government Information: Policies and Sources by Peter Hernon et al.
http://www.amazon.com/gp/product/1563089793/ref=pd_sim_b_2/002-6489600-1562440?%5Fencoding=UTF8&v=glance&n=283155I think our prof told us this is really THE only book that's any good about this subject.
Of course the scope is much broader than Congress - it only has a couple of chapters on the legislative process, and the focus is on accessing information products, but it does cover the legislative process fairly well.
It's really fascinating and informative. If you have access to a college or university library where there's a graduate Library Science program, there's a good chance they have a copy. Otherwise if you can afford $50, I highly recommend it, even though it may not be as deep as you would like on the legislative process. All the other stuff it covers may be worth it to you though.
Amazon page:
http://www.amazon.com/gp/product/1563089793/ref=pd_sim_b_2/002-6489600-1562440?%5Fencoding=UTF8&v=glance&n=283155btw, thanks for asking the question and making me pull this book off my shelf - I think I'll re-read a few sections!