My questions are in reference to this:

http://bruce.grenade.home.comcast.net/circuit.jpg

Background: This circuit is a piece of a larger one that I found on the net for a coil driver. I have simplified the drawing for the purpose of these questions. V1 is a battery (12 volts) and V2 is a FET driver of which the output will be 0v or +5v. V2 is pulsed, so that when Q1 is on, Q2 is off and the other way around.

1) I'm a bit confused as to the purpose of C5 is and how it would work in circuit. Seems to me that C5's cathode will always be 12 volts and when Q1 is on, the anode would also be 12 volts. What am I missing here?

2) How exactly does R6 and D3 function in this circuit? Some sort of gate voltage protection?

Thanks for the help!
Bruce