Training, hours building and first job prospects in America

[Revolutionary]

I'll take a stab at this:

You'll need an FAA PPL to build time in the US, if for no other reason than the fact that nobody will rent you a helicopter if you only have a JAA PPL.

You'll need an FAA PPL before you can get an FAA CPL, instrument rating or CFI certificate. However it's easy to convert your JAA PPL to an FAA PPL -it's a simple administrative procedure.