The E/F are really completely different aircraft, like 20% bigger than the CF-18. The name was retained as a way to sneak a new aircraft through the budget by making Congress think it was an upgrade of an old aircraft.
China obtained a small fleet of UH-60 Blackhawks they received in the brief period prior to 1989 when they were a US ally. These were kept flying until very recently, possibly because some of the parts shared with the civilian S-70(?) operated by Hong Kong could be obtained circuitously.
Owners’ manuals? Please. This is 2019. They’d download YouTube videos.
Primarily American Packard Merlin engines built under license.
You really have to separate out earlier weapons systems from present day systems which are much more complex and depend on large intertwined systems to make them work. The modern U.S. military is highly integrated and a lot of hardware requires support from other systems. And the software in these weapons is now one of the most expensive parts and would be hardest for another state to use without support. The F-35 has 23 million lines of code. A B-29 has zero.