BHB, go ahead and take as many does as you want, no one person is going to put a big dent in the population. Taking a few does will not hurt at all, in fact it will probably do the opposite. By there being less does in the area, a buck will have to look just alittle bit harder to find an estrus doe, which means he will be on his feet more often traveling greater distances, thus making it more likely to walk by your stand during daylight hours.
As for your question about how many does a buck will breed, i have read various reports, but they all seem to say that its not as many as you would think. It seems as though the concensus was anywhere from 2-7 does, although one article stated that a mature buck might only sire 10 fawns in a lifetime.