FULLTONE 70'S FUZZ MID POT FUNCTION?

[Dingleberry Electronics]

Hi!

Still working on this project and I haven't figured out the function on a MID pot of 70's fuzz. (or the melanhead's full beard fuzz)
How does varying Q2:s collector voltage affect the mids? What is the theory behind it?
And how should I set the mid pot when biasing Q2. With the mid pot set with maximum resistance or
with minimum resistance? (or somewhere between...)
And for the last...
The value of the vol pot! I've seen different schematics for the same fuzz with three different vol. pot values!
100Ka, 250Ka and 500Ka. How does it affect the overall sound. Does it affect the frequency response?
What one would think the lower the value the more of the signal is passing it's way to ground. So if I go for 500Ka => more output?
And does the pot conjunct a passive hig pass filter with the output cap? What I understand you also change the cutoff freq. if you
change the vol. pot value.
Am I right or it is just my own imagination?