No. Repeatedly and obviously intentional, yes.
With their car, no. If someone hits you with their fists however, yes, you may retaliate with a gun. If they flee however, i believe you may not chase them down just to kill them. However, i could be wrong.
Depends if they intentionally started a violent encounter with you. Say they punch you, or hit you with their gun, yes, you may kill them.
If they damage you while doing so, yes.