Few questions about baseball rules...

[sodapop]

Answering them quickly would be greatly appreciated!

1 - When and why can the catcher hit (bodycheck) the runner coming to the home base?

2 - What's the difference between stepping up on a base and tagging the runner (touching him to eliminate him)? Why do sometimes they just step up on the base before the runner arrives and he's out, and why does sometimes they have to either wait until he comes and touches the glove while sliding or to run after him and touch him?

3 - What's the difference between a contact and a power hit?

4 - Can someone BRIEFLY explain the difference between a Change-Up, a Fastball, a Slider and a Curveball?

5 - Can a runner steal a base before the pitcher and the batter are in the "ready" stance? By ready stance I mean the batter ready to hit, the pitcher ready to throw, and the catcher crouched. And is there an amount of seconds between the transition of the non-ready and the ready-stance? Is it like 3 or 5 seconds? Or do they just wait until either the pitcher or batter are ready?

6 - If a player catches the ball before it lands (after it being hit by the batter), we know that the batter will be out. But will other runners on other bases be out too, or just the batter?

7 - When can we effectively use a blunt? Sometimes I hear commentators saying: "Oh now < insert name > will obviously try for the blunt". How do they know? Is there a specific game situation where blunting becomes necessary?

Thanks, I know that's a lot but I just want to get used to it!