I did some research online and it appears that my F2 has one 9V battery power the audio functions while the other powers everything else. Is this true? Or are the batteries simply set up in series or parallel?
Yes, you are correct.
A little tip...the F2 does not deplete the batteries equally.
One side is always a little lower than the other so if you are out hunting and it gets low switching the batteries will give you another battery bar for a limited amount of time.