I did my very first open water dives in Cozumel just like many others on this board I'm sure.
1. Yes, Coz is drift Diving.
2. I would say that hands on experience works for most everyone for drift diving in Coz. Experience is always helpful though.
3. The boat usually follows the divers bubbles and then the first person who reaches the designated PSI (usually around 700 PSI) will go to the Dive Master and signal this to him. He will send up his Safety Sausage and you will do your safety stop near the line. When you surface, the boat will pick you up. Each diver will go to the bouy line, do their safety stop and surface and wait for pick up.
4. Fun is a matter of preference in diving. Some prefer the easy drift along that saves air consumption as apposed to finning around and using up more air. I like to think I am flying under water. Some would say that it is easier to take photo's when the current isn't moving you along. Really, I think it's great fun. All the diving is fun so far. Matter of preference.
I am sure there are lots of other good advice on the board for drift diving too.
You will have fun diving in Cozumel, that's for sure, guaranteed!