Just back from Puerto Vallarta. No worries about ice/water/veggies/salads in any of the restaurants that do a serious tourist business. May be different if you go to some small local restaurant; then I'd be careful. Don't think you need any shots. I smoked some Cubans that I got at my hotel; probably overpaid, but hopefully they were real.

Second the Tulum rec. There's also a park with snorkeling and other stuff called Xel Ha; we went there after Tulum. Have fun!!

Here's the link:

http://www.xel-ha.com/