RE: Instinctive or gap shooting??
"Become the Arrow" (Byron Ferguson) is my favorite among the instructional books I have read (I admit I haven't read that many though). It may be in part because I have met and talked with Byron several times, and he is a really nice, down-to-earth kinda guy--just a good 'ol boy from Alabama. It is clear, concise, and easy to read though. Although I don't use the same style he does, it has a lot of great hints and pointers about things that are useful to you regardless of what style you choose. One thing though--I strongly disagree with the section on wood arrows. It may have been true when he wrote it (several years ago), or maybe he just didn't know where to look, but you can get good wood shafting nowadays.
Good luck!
Chad
Long Bows Rule!