2 in 1, Pitching and Injury

[Bandit]

#1. When is the pitcher removed from the pitching position and not alowed to return to that particular position? Speaking I believe both NFHS and ASA, if the coach has made the forth visit to the mound and now has to make a pitching change, can that particular pitcher pitch agian during that game? #2 In ASA, I believe last year, a rule change allowed umpires to kill the ball immediatly when a player was injured and place players where the umpire thought they would have reached. Is this true in NFHS also?