It depends on the level of play. Some allow that if the starting pitcher is removed from the mound, but put in a defensive position, he can then come back to pitch later in the game, but only once an inning.
In MLB, any player removed from a game is ineligible to return to that game. If a pitcher is moved from the pitching position to another position, he may at a later time be moved back into the pitching position.
YES
If the batter got on base with the original pitcher and he scores of the new pitcher, the previous pitcher is charged with the earned run.
Yes. The DH hits for the pitcher and if the DH enters the field of play the pitcher then has to hit for himself
A starting pitcher who is removed cannot re-enter in either league, if he is removed from the game. It's rarely if ever done in Major League baseball, but if a pitcher is removed as a pitcher but placed in another position he can later return to the pitcher position.
Babe Ruth was a starting pitcher with the Red Sox, however transitioned to the outfield in his later years with them. In 1919 when he got sold to the Yankees he became a full time outfielder playing primarily in right field.
The pitcher can re-enter the game as a pitcher later in the game if he is taken out with no trips to the mound or after one trip. If he is taken out after the second trip to the mound he can re-enter the game in any position except for pitcher..
No. In high school baseball, once a pitcher is called out of a game he is done for the day.
Major league baseball pitcher is remembered for his outstanding record in 1904. In that season, his pitching record was 41 wins and only 12 losses. He is also remembered for a wild pitch that cost the New York Highlanders a pennant. This team was later named the NY Yankees.
Yes. There is no obligation to use the DH in baseball. A somewhat confusing question. A relief pitcher can be used AS the DH. However normal DH rules apply and that player could not pitch in the game. A relief pitcher can pinch hit FOR the DH as well. That pitcher then becomes the DH and normal rules apply. I am pretty sure that a relief pitch that enters the game as a pitcher can not be inserted into the lineup for the DH but I could be wrong. Of course you don't have to use the DH but you can't use a relief pitcher in your lineup unless he's playing a position in the field. Yes. When you bring in the relief pitcher, you can at that time have him hit in place of the DH. You can also have him pinch-hit for the DH at a later point in the game. Note that in both cases, there is no longer a DH and all pitchers must hit. Baseball rule 6.10.
Yes.
No. Once a player is removed from the game, they cannot re-enter that game.