I do think that your age will present somewhat of a challenge, but not an impossible one. The questions you will need to convinvingly answer are 1) Why do you want this degree NOW, instead of after working for a few years? and 2) Can you demonstrate that you have the maturity and level of experience needed for you to get the most out of the program?
As for books, the Offical Guide for GMAT review is considered the gold standard. It's published by the people who run the GMAT, and contains something like over 1400 questions to practice. I definitely recommend buying that, but first starting with something like Kaplan's GMAT book. Once you've completed that book and feel pretty comfortable with the questions, then you can start on
the Official Guide. I think you'll get more value out of
the Official Guide that way.
Scott