In regards to your mouse sensitivity issue...I'd err on the side of more sensitive rather than less (i.e. easy to do 180, but more difficult to do precise aiming). Why? Well, if you don't worry about it and keep playing, you should find you get used to the higher sensitivity.
Also, try to track your opponent less with your mouse and more with your eyes.
Doing both those things will drastically reduce hand/wrist fatigue and help you respond more quickly, IMHO.
As regards to ping, haha, great timing. Just posted a
thread on that very topic.
