behenson, you are asking questions, expressing concerns, seeking advice on how to improve.... First, you are on the right track , good for you !
My advice: If you have not already, take a look at the past couple months of posts and read the reviews posted by fellow Scubaboarders. Get a feel for the Dive Ops mentioned and choose your top 3-5 that sound comfortable. Then, contact each one, beginning with your top choice. Questions and info you should include:
Date of stay
Where you are staying
Experience
6 pack boat ?- I would go with this
Private DM- YES ! In fact, perhaps for you and wife a private DM for 2-3 days. One-on-One attention with buoyancy, weight, air, confidence
Rental equipment if needed
Will you need to meet at a pier elsewhere? If so, what $$
Once you settle on a Dive Op- then get your list together of to do's:
Service any equipment you own.
Get DAN insurance if needed-middle plan at least of not top plan
Perhaps get into a pool at home for a review of skills: SMB for sure
Continue to read ScubaBoard !
Now, all of that as I said was "First". Now for "Second"
Enjoy your time, relax and as my Cozumel DM, Pedro Pablo of Blue XT Sea Diving, for the past 11 years has taught me
"Take it very very slow". My DH and I take this advice to heart. And since this is coming from a DM who has logged 10,000 + dives and who practices what he teaches, I have know doubt that slow is the way to go !!!!
Best Wishes to you and yours. Have a wonderful adventure !