Basically, software, of which there's a ton to say regarding F-35 development. All the features required and component integration required them to adopt an agile methodology, moving away from the Ada-style development processes and, arguably hacking things together until they kinda worked. The predictable result is a long-tail of bugs that may never be fully eradicated.
Microstrips have been used in planes for decades.
AR, not VR, right? Pretty sure they were doing that in helicopters years ago. Doesn't the Apache have a 30mm autocannon slaved to the pilot's helmet display, such that it shoots where the pilot looks? I'm no helmet geek, but I think that stuff came out in the 80s.
I suppose the F-35's implementation is cooler, on account of being newer, but it doesn't seem earth shattering to me.
Probably depends, but the way I see it, AR is when you pass the world through but draw stuff on top of it, whereas VR means replacing what you see wholesale. So for instance, a HUD is AR, and F-35 helmet is VR.
The same system also exists for the Eurocopter Tiger
But next time I talk to my CEO I will try this with 'we do some crazy networking'.