Four of four. Hogwarts apparently remembers the Marauders, for better or worse. I'm going to suggest we don't try talking to him all at once, the way we did with James. If he's that close to Halloween 1981, even if he hasn't committed the act, yet, he may be feeling the same distrust we all were then. One on one is probably the best way to approach him.
Harry
Better enough that unless I'm emotionally involved or distracted sneaking up on or lying to me is very difficult. You're correct that I probably can't give you an exact count, but if you can give me some time pre-dawn to recon the area around the bank, I can give you a rough estimate.