Ponce Inlet comes to mind just south of Daytona, Ft. Desoto in St. Petersburg and various areas around Sanibel. No, there are a lot of restricted beaches to kiting in various areas in Florida. There are precautions that often apply. More about that below. As a rule, kiteboarding insurance isn't required in most areas in the USA. It is a good idea to have liability coverage regardless. I would ask the BKSA is their policy covers you in the USA and will potentially pay out in the instance of a claim here. They may or may not but again, it is usually not a requirement to ride in Florida, unlike some areas in the UK and Europe.
There is a vast amount of information on this site about launches, conditions and precautions in various areas around the state. You should look over the following two stickie posts first at:
http://fksa.org/forumdisplay.php?f=89
There are weather/wind stickies in each of the forums for various parts of the state, e.g. for NE Florida at:
http://fksa.org/forumdisplay.php?f=22
Regarding Ponce Inlet, there is some information at:
http://fksa.org/showthread.php?t=3402
Regarding Sanibel, some info at:
http://www.fksa.org/showthread.php?t=2099
And for St. Pete, the guys have a ton of info at:
http://fksa.org/forumdisplay.php?f=10
Have a good trip!