#1
how far away does the bridge have to be from the 12th fret, or where does the bridge have to be in relation to the neck?
#2
depends on what scale u have, but the 12th fret must be halfway between nut and bridge
#3
Stew mac has a scale calculator on their site. But the bridge saddle should be the same distance from the 12th fret as the nut is.