1) There is no way of discovering how much an opponent's proxy bid is. Your best tactic is to make your bid the maximum amount you're willing to spend on the item. That way if you're outbid you have the solace of knowing that you didn't want to pay as much as the winner did anyway.
2) Just line it up on AS and watch the fur fly. No need to do anything more once you've set up the snipe.
Good luck!