#3
What do you want the switch to do? Do you want it to be a pickup-selector, or a killswitch? Do you want it to adjust tone? If so, I think you'd need some sort of resistor as well as a switch.
#4
You mean a switch to go from 'tone on 10' to 'tone rolled down' tones? Yeah, that's definitely possible. You'd have the signal from the pickup's hot wire coming to the middle lug. Then one of the outer lugs would go straight to the volume pot, output jack, selector switch, whatever. The other outer lug would go to a .022 microfarad cap, with a resistor in series, and also to the aforesaid output jack/ whatever.