Pro Mechanics/Game Management

[DevildogUmp]

Hanging out at the local Triple-A park this weekend for 2 games and of course am watching the umpires as much as the game. Couple of questions if anyone happens to know the answer:

1. Batter requesting time - Plate gives time, points to the batter, and immediately gives the reset signal for the pitch clock. Elapsed time for the request, maybe 3 second. Is there any leeway on giving the batter more time before resetting the clock?

2. Catcher goes out to the mound and about 3 seconds into the 30 sec clock, the coach comes out and they reset the 30 sec clock when he stepped out of the dugout. Is there an amount of time the coach gets to make up his mind to have the clock get reset for the visit? 

3. Non-pitcher defensive substitutions - is there a mechanic for alerting the box to the change like you do for the pitcher and batter, or is that just something they just expect the box to pick up on?