It's amazing how much an interested high school student can learn in the course of a few hours by doing the right google searches. Unfortunately, there aren't a lot of guides to some of the best posts around.
(a) use the collegeconfidential search engine. there are many many informative threads in the past. if you really don't want to register, google site:talk.collegeconfidential.com [thing you're looking for], or site:mathlinks.ro , site:physicsforums.com