A few questions about the layout:
It looks pretty straightforward except fo the 3-pin devices labeled "5K" near wire B-25, "100K" near wire B-8, and "10K" on what looks like the "FET" daughter board. Are these some kind of center-tapped resistor? I've never seen something like that.
Those are trimmer pots. It's like a regular pot but these are used inside the amp.
http://www.allelectronics.com/cgi-bin/category/470100/Trimmer.htmlAlso, about the "FET" circuit. Is the actual FET the grey blob in the middle of that daughter board? If it is, I've never seen a 4-pin JFET or MOSFET like that. I thought FETs are 3-port devices: gate, drain and source.
Sorry don't know about that.
There are two connections to a "choke". I'm assuming that the choke is an inductor mounted to the other side of the chassis as is the output transfomer.
Yes that's it.
I guess the "7812" is a 12 V voltage regulator device.
Yes