I'd caution to add getting the TSA approval for flight rating, which is required for non-US nationals. Some more info can be found on
this AOPA page, or the TSA site at
www.flightschoolcandidates.gov
You may also need a special visa that allows flight training, rather than the regular visitor visa or visa waiver.
I'd also recommend getting an PPL(H) by doing the written test, 3 hrs of instruction and a check ride for those with more than 100hrs, as a validation takes upwards of 3 months, and once you have the FAA ticket it is permanent rather than restricted by the validation.
Is it possible to go from FAA PPL(H) (validation or basic) to ATP(H), without having to do a CPL first?