I highly recommend Don Lynch's books and Cameron's Illustrated Screenplay. YES...this IS the script of the movie, including deleted scenes (which will be released next month on the special edition DVD).
The screen play book also had scenes that were not even filmed due to time constraints. (spoiler) One scene was during the sinking, you see a person's view as he jumps and falls past the propellors and hits the water, and another shows the engine room during the break up, the whole area shredding apart with machinery falling around them.
I also recall in the book, there is an extended version of the subs dropping to the ocean floor and exploring the wreck.