New PM'er needs more mash info

I am getting ready to do my 3rd PM. I have read a lot about mash techniques from the Joy of Home Brewing, BYO mag and, of course, HBT. I have concluded that there are many techniques and many opinions. What are some resources for some more in-depth info regarding mashing?
In particular, I am wondering when is it necessary to do protein or sach rests? If I am using fully modified grains, is there any benefit to doing a multiple step mash? What are the resulting differences in the beer whether I do a batch or trickle sparge?

On a larger scope; what's a good source for more in-depth reading on brewing in general?

 

Palmer's How To Brew has a good section on how the mash actually works and different step infussions and such.

 

Chris Holst's Homebrewing for the Absolute Beginner tutorial on eGullet.org is excellent. The third section is about PM brewing with minimal equipment and covers the topic extremely well. Read the whole thing, though. Chris does a nice job explaining the ins and outs of malts, hops, yeasts and the brewing process.

You'll also want to read BYO's Countertop Partial Mashing if you haven't already.

Palmer's How to Brew is pretty much the bible, but go ahead and spend the money for the real paper book. The third edition is significantly updated and more detailed than the free online original.

Chad