Yes, with "license". The last one actually departed from the original plot lines the most, and left out stuff I think is very important to the continuing storyline, but they may be saving those pieces for the next one.
IMHO, the audio books with Jim Dale are superb (both the writing and the acting), and excellent listening after seeing the films. You can get them used, cheap.
Seconded! One of the best audiobook readers out there.
I LOVE Jim Dale!! The only books I have ever preferred to listen to rather than read.