to #2 "And when you come back to the UK, you will have to be taught how to navigate and the correct procedure for carrying out stalls!!"
There is not prescribed way to navigate. The only thing the examiner cares for is that you;
- arrive on time
- and that the method you use is visible to him (ie he wants to know how you're doing it)
Regarding stalls; The EASA regs focus a lot on stall avoidance, while other territories focus on stall recovery. Both have merit.
Please don't think the UK or EASA possess all wisdom when it comes to VFR flying. I have personally experienced they do not; And frankly they don't need to, considering how brain-dead easy it is to navigate over here.
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To the OP:
Personally I would not fret too much about doing PPL in minimum hours. It is not a pissing contest and you will not care anymore once you get paid to fly. You need the hours anyway for your CPL, so consider it part of hour building. Could you have done it cheaper? Perhaps, but when people say you could have gotten your PPL for 12k in 40-50 hours, they are omitting the fact that you already got some additional hours you need anyway.
Personally I would stick with your school and get your PPL; Don't bother changing, you'll get stuck forever doing checkrides etc with another school anyway until they have checked your standard before they can put you up for a skills test.
If you intend to get an EASA CPL MEIR then I would stick with the US, get your PPL, get some cheap hour building going, and then return to the UK for your NVFR, CPL and IR.
NVFR: When I did it my ICAO NVFR was not accepted, so I did the course again. Your mileage may vary, seems to depend on who you ask at the CAA
CPL: Glorified PPL in Europe, don't sweat it. No point converting from an ICAO CPL as it is just expensive (785£ for a skills test alone, no aircraft hire). You might learn more doing your CPL elsewhere, but it won't matter in the end if you stick with Europe and want to save some pennies.
MEIR: The UK is pretty damn congested when it comes to airspace, which provides a great training environment for IR. Also, the UK IR skills test includes a non precision approach. I don't believe the US has NDBs anymore, so this would be something you have to learn anyway. Considering multi engine aircraft in the UK cost an arm and a leg to hire, you might as well get it right the first time.
Just my 2 cents. Best of luck buddy, and make sure you enjoy it.
Disclaimer - I never did any flying in the US and I don't hold an FAA license. My advice is based on my own experience converting an ICAO license, so your mileage may vary.