I went a few weeks ago and had a blast. Everything is available on site from jet ski, para-sail, horseback riding, pool, beach, free food and drinks. Did notice it's $5 less entree if you prepay but otherwise just go and decide day off what you want to do.
Recommend the fish pedicure. Put your feet in a fish tank for 20mins and they eat any dead skin, it tickles a bit. Afterwards get a foot massage and it's only $20.
It is a short ride by cab from the port. I cannot remember exactly, but I want to say it was $10 or so. The staff are fabulous. My husband and I paid for the all inclusive day and the food and drinks were wonderful. My in laws did a couples massage, and it was reasonably priced and they said it was wonderful also. We loved it, and will return if we ever go back to Cozumel