We went there last year and had a wonderful time! We had booked through Carnival then and bus transportation was provided. I think the cost of the park for an adult is around $62. We ate breakfast on the ship and the only thing we ate at Xcarat was chips and salsa for lunch with a couple of lemonades. There are drink machines throughout the park. We may have spent $30 for a family of 4 on nachos and drinks for lunch and a few extra waters and juices throughout the day. We went back to the ship an hour before we had to be, ate, and took a nap.
Enjoy! It's a beautiful park! More to see and do than you can fit into one day!