Only vague possibilities regarding the source of the pop. A piece of equipment turned on or off during the recording that either fed a signal to the mix but wasn't being used, or
a piece of equipment that sucked enough power on start-up to make another piece of equipment fart. Much less likely.
Yeah, I'm too close to FV Guitar Satan for my plastic to ever relax. It screams when I take it out of my wallet.
As to the blip removal; I've only tried some really Flintstone techniques in pursuit of such .wav file modifications. They sort of work... Close in on the suspect audio track timewise as tight as possible and drop the audio 3dB at a time until it's not as annoying.