Then you have to be very lucky. I think in real life, you can go prone and shoot same time but you will have no accuracy at all. Same ingame. So maybe one time out of thousand you'll be able to kill someone like that
You can but you risk tearing yourself and your equipment up while dropping, but if your ass is on the line with the adrenaline pumping and some nut looking at you like he is wanting to cut part of you off and shove it somewhere else just for the hell of it after he shoots you I doubt you will feel the fall at all. In real life you have way better chance at least of hitting your target going prone before you could ever jump sideways around a corner and head shoot the enemy as your feet hit the ground as happens a lot in AA. Even knowing pretty much where they are you still don't know for sure if standing. crouched, prone or if they have some sort of cover.
Let alone the simple fact you can't jump and land and stay on target. The upward momentum and major jarring of landing is going throw you aim so far off be lucky to hit them at all.