Helicopters don't typically crash due to loss of power, as the blades provide lift even with the engine off. Helicopters can 'autorotate' down to the ground and land safely even without engine power.

Is Escape the vehicle showcase? This could very well be intended behavior; you ARE in a stolen vehicle which is 'on their side', after all. Enemies in the countryside might also have worse intel; enemies share intel with each other, so enemies in closer groupings (cities) would have better intel on you, and would know you're an enemy.

If you're referring to the immersive "screen in a vehicle" view, the FPS drop is probably due to the extra resources required to make that PIP view of the FLIR camera.

It's probably that your underwater weapon is precisely that -- a gun designed to be used underwater. It's less effective above the water from what I've noticed.

Yeah, VSync defaults to an integer division of your monitor's framerate if it can't attain the refresh rate. Not a bug, you just can't run the game at 60fps.

I wouldn't consider this unrealistic. The baseline for the "is this good AI behavior" is whether or not players would do the same; if I were OPFOR, and I had grenades, I'd darn well use them. These AI also represent trained soldiers, who (hopefully) should be trained in how to use their weapons, and therefore should be at least fairly accurate.

Fair enough. Perhaps groups of AI could 'coordinate' so that they don't over-employ grenades? Only one or two would employ their explosives at a time; that'd be less wasteful, more realistic and less frustrating.