I HIGHLY recommend Scuba with Alison for a beginner. We dove with her when we had about the same number of dives as you, and they were our first ever ocean dives. She is incredibly safety conscious, checking with you about your air, always counting to make sure the group is together. She goes up to the safety stop with you to make sure you stay at the right depth and watch you get on the boat. We saw her go after a few people who unknowingly went below the agreed upon depth and pulled them back up. (She also gives advanced divers more freedom to dive deeper depths, poke around a bit without her- but on the first dive she would probably expect your buddy to stay close to the group.) Her boat also has two positions you can giant stride from if you don't like to roll. IIRC, she wants you to do safety stop at 800 psi and be back on the boat at 500 psi. She takes care of all your gear but the wetsuit- full service, gear was waiting on the tank when I got in the boat.
We also had a great experience with Tres Pelicanos, and I know they would take good care of a beginner as well (I had a freak out rolling off the boat and then my mask was leaking on the surface so I took some time to fix it, and the DM was literally willing to hold my hand on the descent, which I didn't really need, I just needed a moment to collect myself, but it was good to know they will take care of you if you need it), but I think with them, at least on the first day, I'd want a private divemaster just because of the looser group structure they use (or, if you are comfortable, just stick with your buddy). Intermediate and advanced divers are given a great deal of freedom, even on day 1 it seems- you can poke around as much as you want, and you do your safety stop on your own/in a buddy pair (DM will send up SMB if you can't). The DM didn't check with us on our air, or seem to see that we stayed above agreed upon depth (in fact, one swim through he went through was below the dive briefing depth.) Some people stayed in the water longer than the DM did- both DMs were pretty hands off. (Due to poor visibility we had one dive where we never really saw the DM after the initial descent.)
They ask you to go to your safety stop at 600 psi, and not to go into any swimthroughs below 1000 psi. There was never a 'back on the boat' amount stated. They take all your gear AND your wetsuits. They didn't put the gear on the tank for me in the morning, but I bet they would have if I asked (it's not that big of a deal).
If you need it, both ops have great rental gear- though we preferred Alison's personally. Both ops have great fast, comfortable boats and wonderful captains.
If you stay in town, Tres Pelicanos gives you a ride to the marina, with Alison you need a cab. If you stay at a resort south of the marina with a pier, Alison will pick you up (email her for a list)- TP also picks up at all those, and goes up north a little bit at least to El Cid (again, email for a list).
As Sharky60 mentioned, DMs always accompany divers in the water on boat trips - unlike many other dive destinations. Underwater park rules require it. Still, as a newbie on his first time with Coz drift diving, hiring a private DM the first day would be money well spent. 
