I have found that deer are more likely to let me drive by them, then run. I truly feel that walking scares them more.

The only thing I have found, is that the sight of the ATV can scare them, when it is just sitting there parked. So I would recommend a camo cover for it.

I think 100 yards is fine, unless the wind will be blowing directly from your ATV to the stand, then I would make it 200 yards.