As always the O'Reilly books are pretty good.
Get the O'Reilly Apache Cookbook. Apache, The Definitive Guide has some good stuff in it but it's very poorly organized, IMHO.
IMHO, the book for all things MySQL, both programming and administering a server, is MySQL by Paul DuBois from Developer's Library. It's had a 4th edition out for a good while now but I've still just got the 3rd. It's the only MySQL book I've ever needed and I both run LAMP servers and write code using it nearly every day.
Apache's own documentation is very through and you should familiarize yourself with it.
Likewise, Debian is the best source for much of its own documentation.
Debian Lenny willl EOL and lose security support in less than a year. I strongly recommend upgrading to squeeze.
Debian Wiki:
http://wiki.debian.org/
Debian Documentation:
http://www.debian.org/doc/
Apache documentation (find the right page for your version)
http://httpd.apache.org/docs/2.2/
Note that Debian has many system tools for controlling Apache that override the default ones that come with Apache itself.
use 'invoke-rc.d apache2 <command>' to start, stop, and otherwise control the server.
use a2enmod, a2dismod, a2ensite and a2dissite to enable and disable modules and site configuration snippits.
When it comes to performance tuning a server for a high bandwidth ap, I'm not aware of any books. There are simply too many variables than can come into play and it becomes as much an art as a science.
I made a few Drupal sites before switching to Concrete5 and later Django. The key things I remember to getting tolerable performance was throwing a ton of RAM at MySQL, using apache's static content caching, and opcode caching for php