not trying to be a smart ass here but do a little research on electic motors generators and transformers. a pickup is basicaly a generator. the motion of the string makes the magnet vibrate, the the vibrating magnetic field causes and electrical current in the wire and well the amplifier just amplifies that. any way if you use a weak magnet you will get a weak field and there for a weak signal if you use a larger wire you won't get as many turns around the magnet and so you won't get as strong of a signal, and im not sure but i don't even thing you will get a signal with a faris metal but like i said im not sure.
now if you could find some really light gauge gold wire that could be interesting because it has less resistance than copper so you could use a lighter wire and get the same amount of power so and so you could get even more turns and that means even more power out of the pickup.
btw any one feel free to correct hell i dont' know, i just know a little theory.