hello forum. i was wandering. on electronic controled idle valves, does the valve, completely closes when you press the throttle? or it remains on the position it was before you pressed???

This is a matter of taste.

i was suspecting something like that... cool! thanks allot

Yeah thats exactly what i wanted to know... for years!.

What kind of strategy do OEM's use?. I would be GUESSING that the IAC-valve would be commanded closed at higher rpm/load... so as to minimize turbulence/restriction in the throttle body?

... anyone?

No idea what OEMs do, but I prefer it to stay at a fixed open value before trying to command idle when you let the throttle off. It is just smoother in my experience. I want control over that value though. Larger throttle openings it doesn't really matter unless it's a massive valve I would think, even then probably doesn't matter depending on plenum design.
Like Fred said, whatever you prefer - which you will find out with tweaking.