1) Not sure how much, but you want to adjust to get the highest vacuum rating, regardless of what it is.
2) start at 2 turns out.
3) set the timing with a timing light at 10 degrees, if you don't have one get one. If you insist on doing it by ear, set it at the highest reading also.
You should not be idleing at 900rpms. It should be about 750 with and auto.