FAA medical is not a problem as there is a doctor's office at Naples Airport all of 30 yards from Naples Air Center's front door. USD75.00 or thereabouts.
I would agree also with the concept of getting as many of the writtens done here before you go.
You can do them out there but as one PPL student who was out there same time as me discovered, it eats into your flying time and when you should be concentrating on the practical aspects of flying, you have to cram your head with all the theoretical stuff.
I assume you're going to do the JAA PPL but also consider getting the unrestricted FAAPPL on the back of it>
Takes the hassle out of going back after your PPL and doing shed loads of hour building.
You will as someone else said need to convert yourself when you get back: US flying is very relaxed but having said that their R/T is pretty snappy and you will find yourself sharing the circuit with Biz jets and allsorts.(I followed a B17 and a Hudson in in February.)
One last point: The weather: Weather from june onwards can be b***dy hot and humid with thunderstorms at 3pm every afternoon and if you leave it too late in the year you may even get a hurricane.
Whatver you do get out there and enjoy it: NaplesAC is certainly an excellent place.
Cusco