Sounds like a plan.
AquaWorld is okay. There are far superior ops to dive with on Coz proper, but you have to get to them under your own power. For a first timer with time constraints, AquaWolrd makes it about as easy as it gets.
Problem with AquaWolrd is that it takes large groups of mixed experience divers, which means you won't get to the most challenging sites, like La Garganta del Diablo (Devil's Throat), and likely will have some divers in the group who are borderline competent (obviously these two are related). Nonetheless, you should get in some fun diving. Coz has very few uninteresting sites.
As for ops on Cancun, I like Solo Buceo
http://www.solobuceo.com/ . Blue Peace was another fav
http://www.bluepeacediving.com/ , but I'm not sure if they're still operating. Except for a couple of advanced sites, e.g., Ultrafreeze, which usually take some planning to arrange, i.e., getting a boat full of qualified divers lined up, Cancun diving is pretty modest. But, it's still worth doing.
Cancun restaurants are not my forte, but I do like Bogart's (very classy & not far from where you are staying) & La Habichuela (Spanish for green bean; downtown so you'll need a cab; get the shrimp concoction that comes in a coconut).
Have fun.
DocVikingo