If possible always demo.
I am shure there are some shops in Miami you can demo.
Most brands of bindings and boards work together these days.
If you want to get bindings that work for more than one rider then they are avaible, CWB makes the Torq with the hinge tech thats sells at most shops for 199.99 and the size ranges are xs/med 5 tru 8 L/Xl 9 tru 12 and you can buy them with the CWB Sol board as a package for 329 at most shops.
Bindings can easyly be swaped out on the boat if you have a phillip head srewdriver in most cases.
Lessons are always good if you want to learn the fundementals and get better faster for shure.
Best of luck to ya and welcome to wakeworld.