Medical
Just a point on the medical - either a current medical for your 'original' PPL OR an FAA is fine. It's in the docs online somewhere.
I had my piggyback FAA PPL issued with my UK PPL and a FAA class 3 medical, since I've lived this side of the pond for 5 years and its a bit difficult to get to the nearest CAA doctor. I guess it's all to do with validity - my UK license is valid (one of the old lifetime ones), just not current in the UK without a medical.
Cheers,
Gareth.