The Fiesta Americana has been recently completely remodeled and is now all-inclusive. Looks very nice.
most hotels/resorts and most dive ops will pick up at most piers, with a few exceptions.
Dive with Martin is still a very good choice for a dive op. Low prices and very good DM/Instructors.
We have been staying and diving with Blue Angel Resort/dive op for a dozen years now. Nice property, about a mile south of town, small 22 room hotel with all rooms facing the ocean and pool, free breakfast (maybe on dive days only, but possibly all days, I usually just eat something in the room as neither of us are morning people and barely make it to the boat as it is).
BA offers aluminum 100's as a large tank option, I use them on all dives.
If you don't dive with BA, most dive ops will pick up at their pier. Or if you stay somewhere else, they will pick you up at that pier, as long as it's south of town.
with a group of six, most dive ops will probably put you on your own boat.
I have also heard crime is up, but I was just there for 18 days and personally had no issues or even heard of anything happening while there, and we spend a lot of time running around "in town". I THINK the increase in crime is burglaries and crime on locals not so much on tourists. It has a lot to do with the current political climate on the island. Long story, but basically from what I've heard, the new Mayor is causing a lot of problems.
other dive op reco's:
Aldora - by far, one of the best dive ops on the island, they offer steel 120's
BlueXTSea - boutique diving, good for a group.
Bottom Time Divers - Raul Plates is a GREAT DM/Instructor. Very safety minded and great at finding little things. One man op also good for a group
Tres Pelicanos - very nice wide beam boats. Good DM's & service. Won't pick up at Blue Angel, but will at most other places, I think.
I would imagine most dive ops would provide you with large tanks, either aluminum 100's or steel 120's upon request.
if you have about a 1/2 hour to kill, here's a link to a segment I did for the radio station a couple years ago on finding a dive op on Coz. The information was gathered from a poll we did here on the Scubaboard and interviewing Coz divers ...
The Shark Tank radio show: Tips on finding a Dive Operator on Cozumel ...
feel free to PM me if you have any questions ...