How tall your kids have to be to get in the rides

It depends on what the rides are.

There's a multitude of rides that any kid can jump on. They even have a list of rides for 2 year olds. With the exception of about 5 rides (38/40+ inches) there are no height requirements.

They tell you on their website.

Well everyone can go on Coast cruise. Fairytale brook as well. I think like 35+ for some of them like coastersaurus

There is one ride for any age and height: Coast Cruise. Fairy Tale Brook is also heightless, I'm rather sure. And the Duplo Train. :P