@tlc:

"The Essential Guide to Learning Blender 2.6" has about 25 pages on it. The book does a reasonable job of covering compositing using blur, alpha over, lighting effects, and vector blur among others, in other words, that ones that will be used 90% of the time, and it shows how to split them into rendering layers and recombine them. Not bad. It doesn't get into the lessor used nodes, though.

The master book for compositing is "Blender Compositing," which I also have. It's for 2.49, but doesn't really matter since the nodes in the Node Editor have changed very little. That book isn't just for the Node Editor, by the way. The author, Roger Wickes, takes a broad interpretation of the word compositing, or combining, so theres a great deal about perspective, and masking techniques. It's rather heavy duty, but so is the subject, and he uses several projects to demonstrate.

Retopology: I didn't see anything in the index in "The Essential Guide to Learning Blender 2.6" on retopo, but that's more of a tool than a subject, IMO. Blendercookie has a decent retopology tutorial here:

http://www.blendercookie.com/2010/08/30/retopology-and-normal/