What is this PCB component?
The circular trace is an inductor, what it's doing in the circuit is hard to tell, without looking at the other components in the circuit. It looks like it's connected to a ground plane along with the screw. They removed the ground plane around the inductor to avoid capacitance with the ground plane. The thing could be an antenna. 



The "spark gap" really depends on if it is there is a gap (which isn't apparent from the picture. It's either for ESD suppression (which might make sense if its attached to a screw. If there is solder mask (darker green hourglass shape) with copper underneath, then it's simply to ground out the fastener .