If the player shoots back, she will die instantly regardless of where she is hit, so kneecaps won't do.
I think the little bit of extra zoom independent gives you could be beneficial, usually I tend to prefer affected since the zoom can be a little jarring however I feel like the game is slow paced enough that it isn't really an issue.
Also, increase the volume of your game so you can hear enemies talking or making other noises using headphones helps to hear where the sounds are coming from.