1) 1/8 turn is what I use, after that I just nudge it to fine tune it.
2) Or you can spit on the motor, if it boils off quickly, it's too hot, if it just sits there, too cold.
3) Highest I've heard is 260-275.
4) anything higher is too hot.
5) Idle for a few tanks, then a few on light throttle, then a few full throttle ones (how you would use it normally, say, in a race). Varies from engine to engine.