The force that is produced while swinging the bat and the throwing of the ball.
Usually because the ball hits in what you could call the weakest part of the bat. If the ball hits directly on a grain, or a weak part of a poorly made bat. the bat will crack. Also, the ball can break the bat at the handle, where the bat is thinnest, due to the massive amount of force the ball is traveling with as it comes in contact with the bat.
Yes. It also sounds like a crack.
It depends on the player and how hard they can strike the ball, some can really crack the ball.
If you swing and miss and the ball hits you, it is a strike and a live ball. If you swing and the bat makes contact with the ball and the ball hits you while you're in the batter's box, it is a foul ball and a dead ball.
The hitter...
fairball
If the baseball hit the ground in foul territory, the ball is a foul ball. If the baseball hit the ground in fair territory, and the batter/runner is still in the batter's box when the baseball hits him, it is a foul ball. If the baseball hit the ground in fair territory and the batter/runner is out of the batter's box when the baseball hits him, the batter/runner is out and the ball is dead.
In regular baseball rules, the ball is still live, even if it hits the ground first, until it hits the batter, then it becomes a "dead ball". If it never hits the batter, its still a live ball.
The force and strength of the blow of the baseball bat propels the baseball forward.
It is a ball that the batter hits on the ground. Contrary to a fly ball that is hit in the air.
A batter hits a ball off home plate
The ball is still technically in. According to the rules of volleyball, if it hits the net and goes over, it is still in.