Hey WaveRipper,
I think that it is fair to take your share but to allow the surfers their rightful waves too. By pulling off a nice wave and calling them on, usually shows respect and consideration.
If the break is crowded with surfers I usually move on. If there are a couple of surfers out there in 25 knots, blown out crap, I give em space but take what I want. If I see them paddling for a wave I pull out.
It's a bout fairness. If you do pick off a nice one make sure you rip it to bits and don't kook it.
With regard to distance to surfers, as far as I know, there are no hard and fast rules in the real world. Just don't get too close, they'll let you know if you are too close.
Hope this helps,
Good winds,