All strats with the old style 6 screw bridge wack out of tune when the tremolo is used.One thing that works well is,if your bridge is set flush to the body,after your done useing the arm give it a yank up that gets it pretty close to back in tune. I wouldn't install a l;ocking nut cause with out microtuners ala.Floyd Rose you can't retune the guitar when the strings stretch a little.
As far as the nut its self I've allways like brass nuts these cost about $50 to have made. ou could also try rubbing a little pencil lead into the nut slots as lubrication for the strings,but old strats never stay intune under tremolo use ask Jimi Hendrix.
As far as the 60 cycle hum from the pups that can't be helped.You can replace the pups with stacked hum canceling single coils like Dimarzio's HS-3 thats a nice pickup.
Stock single will e quiet but make sure your not near any transormers,asically any appliance like TVs etc... have transformers and will cause you to hum if the appliance is on.Also playing in bars most of the time stock singles will e fine,except for the time you have a beer sign right nex to your rig,then its a disaster.
Noise gates are OK but cut the tail end of your sustain off if you can live with that they can eliminate the hum.

[Edited by Guitar-Sam on 01-16-2004 at 09:26 PM]