Thanks for your thoughts, o seasoned veteran of Cozumel trips! Just saw your "August roll call" post. I hope you have a fabulous birthday there!Ok, well, it's the basic backroll, stay with your assigned buddy and the group, and on surfacing wait for the boat and ladder. There will be a briefing before every dive you should listed to carefully.
Nah, it's much more than a start. You should know what you're doing by now. Do put your info in the first shot and protect it so it can't be erased, and pass it to the skipper before your fins. I assume that you have DAN Dive insurance - essential, but comprehensive Trip insurance is a good idea still as you are leaving the US, your medical insurance is probably not valid there, and bad things happen at times.
I'm one of the luckies who has a Medicare Advantage plan that covers me out of the country. Go figure. And have trip/dive insurance.