#4
Instead of using a pot you could do a full/half/no volume setup with some resistors and a switch.
#6
SP3Ts and 30 cents of resistors aren't that rare

Pots in guitars are used as variable voltage dividers referenced to ground. Use a 500k resistor between the signal out and ground for full volume, short to ground for no volume, and measure the resistance of a 500k log pot turned halfway up between pins 1,2 and 2,3 for a half volume voltage divider where the output is between the 1,2 resistance and 2,3 resistance in reference to ground. Here's the half volume
____
In |
[ ] (R of pin 1,2)
|---------------------- Out
[ ] (R of pin 2,3)
|
|
\ / Ground

Full volume

In___
|
|---------Out
[ ] 500k resistor
|
|
\ /

No Volume
In___
|
|
\ /
#7
I think you can do it with a dpdt on/on/on. wire all the poles on one side to the pickup and on the other set of poles, wire a resistor from the middle pole to either the top or bottom pole, send that pole to the output, leave the remaining pole empty. that way you get 1. no output, 2. half volume, 3. full volume. plus you get a killswitch also lol, you just have to experiment with the resistor value, or use a trimpot so you can adjust the level. I suppose it could be wired either before or after the selector switch depending on your preference. just a wild ass guess even though I do have quite a bit of experience, that mod hasn't crossed my mind.
Takes a Knockin' and Keeps on Rockin" DOA #08-01502