Can I wear flip-flops or just water shoes ?

Some rides allow them some don't. The ones that don't have storage bins at the entrance.

Is better of you wear water shoes...

You can wear either.

You can wear either the surface can get extremely hot to walk on so best to wear something

There are lockers available to store your belongings. Water shoes can be worn on the rides and throughout the park, sandals and flip flops can be worn in the park but not on the rides. Many people leave their shoes/towels on the chairs on the beach throughout the day; another option.

You can use water shoes on any of the rides that use an inflatable but you can't wear anything in your feet on the body slides and they will turn you away, i.e. they won't even met you hold shoes. There are net storage shelves near the entrances of the rides.

Barefoot or with water shoes

Either but you are not allowed to use any type of shoes on the rides/slides