Sounds like you have an oscilation issue going on. This sometimes happens with high gain pedals.
I think I have heard that adding a 100 Ohm resistor from +9v to the board might help taming oscilation issues. At least it removes the high pitched noise coming from a cheap power supply.
If the power-supply is the source of the high pitched noise, you could do a search for "Huminator" which is a small circuit that I allways add to my builds, in order to elliminate pedal-power noise when using chap power supplys.
Bad ground connection can also result in oscilation on some high gain circuits.
This happend recently with my Marshall SupaFuzz build, and reflowing the solder fixed the issue...
Check these videos and see if this is what you are experiencing regarding the high pitched noise:
https://www.youtube.com/watch?v=bv54-vZnqv8https://www.youtube.com/watch?v=julbbj4R3KoThe issue about dirty bypassed signal sounds like you have a solder bridge on your switch, making it bleed trough into your bypassed signal.
Thats where I would look first, as a bypassed signal should be clean if you have hooked up the switch correctly.
Anyway... I'm no expert, but these are some of the things that pops to mind when reading your post...