[Imp]

Helicopters protect other helicopters as described above, though thought only happened at a range of 2 possibly 3 with infantry. Possibly further against a machine gun.
Its a preemptive strike to protect the other helo from being damaged or running and perhaps therefore taking extra fire.
Helos do it far more than other units but I assume thats because they run if taking fire far more than other units & cant fire off a smoke discharger.
Same mechanics as firing first at a missiles firer before it takes the shot to try & at least spoil it.
Easily managed as said by turning weapon range down to 3