please answer my questions

i'm not exactly very good in chess. (yet!) but im not so sure about the rules of castling. among the many people i've fought with, almost all of them have different rules on castling, and so im not sure which are right and which are wrong. i really want to know a few things, like:

- can  i castling after a check?

- can i castling after my king moved?

- can i castling if a square in between is in check?

- and can i castle if my rook has moved  but came back to its original position?

if possible, please give me the complete rules.

thank you :-)