No. Pitchers can re-enter once in Juniors and above, but there is no re-entry as a pitcher in Majors and below in Little League.
If he is skilled enough
No
Only if the pitcher warms up on the diamond.
Pat Venditte did, so yeah.
46 feet
For little league they are usually 46-60 meaning 46 ft from pitcher to catcher and 60 ft from the bases
Honestly, it varies. I've seen short little league pitchers that are the best. But speaking from what experts would say, the upper 5 feet, 5'8, 5'9, etc. Less then that as well, though. If your a little league pitcher, or your son is, don't let the lack of height get you down. Anything is possible.
one game
from 50-80 depending on the pitcher
No, he can not. Since he does not have the ball he will be called for interference.
in little league you have to wait for the ball to cross home plate but every level after little league you can steal at any time you want to no matter who has the ball or where the pitcher is or what he is doing.