Hi, Leonardo! A Magic Your Way ticket with Park Hopper option allows you to visit any of the 4 theme parks (Animal Kingdom, Magic Kingdom, Epcot, and Hollywood Studios) and you can hop parks anytime during your day (Breakfast in Magic Kingdom, afternoon and evening in Epcot!)
To be able to go to the water parks, you will need to add the Water Park Fun and More option. You can upgrade your tickets at any ticket window. Your other option would be to simply buy a 1 Day ticket for either Blizzard Beach or Typhoon Lagoon. For tickets and pricing, click
HERE.
I checked on La Nouba, and it looks like there will not be any performances during your stay. The theater is scheduled to be dark May 17 - May 31. Sorry for the inconvenience!
Have a great time on your vacation.