Re: "Best" Book/DVD on fly casting mechanics?
You Tube is by far the best resource I can think of there is. The second best video is that which you shoot of your casting. It will help get rid of the bad habits you mentioned.
The best website other than here, has some very advanced stuff but also a lot of basic instructional stuff. It's called Sexyloops.
Best part, all free. All with far more information than you can get in a book or video.