re: Poker & Best Book?
Aliengenius has a couple of very good posts on poker books - I think at this stage he owns almost every single one that's ever been written. Anywho, do a search on his posts on the topic and you'll find they're most informative.
For my money:
Phil Gordon's Little Green Book and Little Blue Book are both very good. The green book is theory, whereas the blue book is practice (ie: it's all analysis of real hands). He's very easy to read, and he really focuses on how you should think about poker, and how you should work your way through hands. Not so much "You should play this hand this way" as "You should think about X, Y and Z, then make your decision". Recommended.
The Harrington on Hold 'em series is very good if you're a tournament player, it gives you some good grounding in how to respond to various tournament situations (when you're short stacked, when you're heads up, when you're on the bubble, etc.). Gives very good definitions and guidelines on a few useful moves (like the squeeze) too. The quiz sections at the end of each chapter are very good as well.
I'm re-reading Killer Poker - No Limit by Vorhaus at the moment and, despite the cheesy title and awful, awful intro by Mark Seif, it's a really good book. What I'm finding especially helpful is that it encourages you to do a lot of self-analysis. It also covers stuff other than the cards, like the frame of mind you need to be in to win, how you should choose your games and when you should choose to play, etc. Deals mostly with cash games, but has some tournament content. Highly recommended.
I think if you can get your head around those three authors I think you'll be doing very well.