Gordy,
The point (1) of last point, ie his FAA ATPL(H) satisfies 'issued under this part' as it includes instrument privileges,
BUT,
I'm not 100% on different class and category in his case.
Strictly speaking, meeting aeronautical experience, one can do CPL(H) to PPL(A) despite some FAA CFIs saying otherwise, but logging the FAA PIC time etc, can be sticky point.
He could also combine foreign (ICAO) and FAA commercial and instrument, mix'n'match, but if he doesn't have any fixed wing licenses outside FAA world, then I'd rather get specific interpretation. Or are you going by the fact that 'different/same class category' is not mentioned, ie it doesn't matter?
Definitely get the ATP written by end of July to avoid the extra hassle coming up. FYI, Farnborough is booked out, so is Paris FSI according to a post elsewhere on pprune. I had it direct from FSI UK.
That is, if you are happy to rent/pay or secure some job to knock off the fixed wing hours as per 61.159.
Also, don't forget that to get twin ATP, you need 50hrs in class/category It can be mix of your dual training for FAA ratings and any work/renting.
Another thing is, if i the end needing to do FAA commercial fixed wing first, then due to the requirements of initial twin commercial, it's easier/faster to get single engine first and then it's proficiency based for twin add on. FAA initial commercial in fixed wing needs to be done in complex (RG/VP/CS) and you need 10hrs of training in complex aeroplane, but can do some twin time which is still complex for ASEL - single eng comm checkride first. UNLESS you want to rack up the twin time for ATP during your commercial and isntrument training in US, that is. Then you're still left with job or renting of 200+hrs. Maybe somewhere in light twin ops considering your helicopter hours.
Can you leave your helicopter job for few months to a year, to get all this? OR use time between 'hitches'? Can you work in the US/work rights? I'm sure some Part 135 ops job after enough hours/training in twin could be viable considering your heli experience.