They could indeed -- but that could be lessened somewhat by the pattern of connecting the strings in series to make the equivalent of a non-inductive wirewound resistor. (Unless you really want to amplify each string separately, this should be possible. Just connect every other string together at the nut (tuner end), and the 2nd and 3rd, and the 4th and 5th at the bridge end, and pick up the signal between the bridge end of the 1st and 6th strings. Similar (with fewer total loops) for a bass. The only problem would be with an instrument with an odd number of strings, such as a 5-string banjo -- which I've never seen with pickups anyway. :-)
This would not do much to cancel hum from a small close source, but for any reasonable distance, it would be fine. (Hmm ... perhaps if you had one of the old Accutron watches, you might pick up from that. :-) I do know that they could be picked up with a close coil or insufficiently shielded tape head.
Agreed. But don't most "serious" audiophiles fit that description?
If you are pumping enough amps into that 8-ohm load, you *might* see a bit more (measurable) voltage drop in the 12-ga. wire -- but *I* don't want to be in the same house with those speakers, no matter *how* inefficient they may happen to be. :-)
There is adequate reason to use heavier wire gauges in sound reenforcement setups for rock performances in large venues -- but even there I don't think they use anything *that* big -- except to route power *to* the stack of amps. :-)
But the image of winding that stuff into a pickup coil just has to bring smiles.
Enjoy, DoN.