Barry - Those are not 4 micro switches. It is actually 2 switches, and 2 trim pots. The trim pots are for output of the pre-amp. This guitar has PF5 electronics, and your 77 has PF6. It's basically set up like your 77, but the trim pots for the output are on the face of the guitar instead of the rear. There are also 2 hum cancelling trim pots, but those are inside the control cavity.
You are right, the plate between the 2 pickups is the cover for the 2 9 volt batteries. The hum canceller is mounted inside the guitar in a pocket under the tailpiece.
I have been watching that guitar for a while. I am glad someone got it who will appreciate it!
Michael