Welcome Dave! I haven't read anyone's trip report who has stayed there yet -- so you be sure to write one. Costa Maya was another resort but was sold, and it sounds like it could be ok. Mexico Rocks is a great area. You won't be close to San Pedro - but you will get to enjoy the quiet and natural beauty up there.
You can buy alot of different beer, but THE beer, the local beer, is Belikin. You will love it. Sorry that I can't remember what the price of a case is, I had it delivered for my arrival, and it was added to my tab. Easy to stock up on groceries. Just let the folks coming to pick you up know that you want to stop and buy groceries before you head north on the water taxi. Yep, you need a passport. Costa Maya (Chris) follows this board - he can probably let you know more.
Enjoy your holiday, you are gonna love it!