If they catch, he should throw nasty 85 MPH breaking balls to 2B/3B to deke the runners. They'd peek to think it was going wide and ease up or run through the bag, just enough to make a YouTube highlight reel or SportCenter's Top 10.
Ironically, a lot of closers are converted catchers since they have cannons for arms and tree trunks for legs. If there's a backup on the roster or their bats are sub-par, the coaching staff will often give them a shot to be a closer. Some examples: Troy Percival, Jason Motte (I played against him when he caught and his arm was legendary), Carlos Marmol, and Kenley Jansen.
For sure. And you can spot the former pitchers who end up in RF, since they have cannons also. Kind of like how receivers who can't hold onto a football end up as cornerbacks.