The Boy Scout Fieldbook is pretty good, too. It has several chapters on camping and backpacking, and some general guides to various parts of the country. Most of the information is fairly current although, like any book, the gear information is somewhat behind the times.

Unless they've recently revised it completely, stay away from the Backpacking Merit Badge handbook, though. The last version I saw acknowledged that internal frame packs could be had with a little effort, but didn't really think they'd catch on for backpacking. (OK, that's a bit exaggerated, but not a lot.)

I'll toss a copy of Colin Fletcher's Complete Walker IV into the package I send you - it's a huge book, but if you're into all that phsyics stuff, it should be a piece of cake for you!