Well, set it at 13.2 mm and see if the VF signal is in the middle range. Lots of cars idle a bit lean so it's no big deal. Besides, the lambda system (O2 sensor, ect) will compensate to a point.
On an N/A car the screw effects idle mixture more than on the turbo because the AFM measuring plate is almost closed at idle and the air that sneaks around it tends to take the path of least resistance. On a turbo it's a different story because the AFM is free flowing.
Yes, that site is a good place to start. Lots of good things on there as long as you can sort out what applies to our cars and what doesn't. I haven't been there in a while but it was the only place I could come up with a 5 gas chart without scanning the ones I have.