The "non-snapback" variables control how quickly the controls move to maximum. For example increasing the KeySteerSpeed will mean that it will take less time for the car to turn to full lock when you press O or P.
The "snapback" variables control how quickly the controls move back the the neutral position. For example, increasing KeyAccelSnapBackSpeed will mean that the time between letting go of the accelerator (Q) and the accelerator moving to zero throttle is less
I hope those babblings made some sense, I hope you enjoy it - although I think it's 100 times better with a wheel
If you find good key steering settings please send me them and i'll try them out