Anyone that can't attend the Live draft will have their picks done through their pre draft ranking and the draft will move on.
If an autodraft is selected the draft will automatically be done according to everyone's pre-daft rankings. Auto draft means exactly that. It will be done automatically without any intervention.
I can't add to what Sightly Stoopid said, because he is exactly right. I will say, though, thought, that live drafts are far and away much better in terms of the overall fantasy baseball experience. Unless you absolutely have to do an autodraft, do everything you can to draft live.