^ For UCM reversals, hit the action buttons repeatedly, your player will usually punch them in the gut or something and throw them off balance, at this point, start shaking the right analog stick, and it should reverse.
As for the other questions, not sure about number 2 but for number 1 you've pretty much hit the nail in the head, your best hope is just to go balls out and keep climbing for that briefcase, because in the first 5 minutes everybody usually ends up in red. I suggest storing a signature move so when another person climbs up the ladder to join you, you can hit them off immediately.