Some quick craps questions (simple).

[resboard]

I have never played craps in a casino, only in play money online. When my brother played in a casino he said you have to bet certain amount on the numbers so they can pay you out easily. I am going to vegas next week and don't want to look like an idiot, so can someone help me figure out how much i will have to give the dealer.

Lets say its a $3 crap tables. How much do i have to put on 4&10
5&9
6&8

And i guess my final question is... When you have money ona number and it hits, they push you your winnings. How do you tell them you want the money back from the number?

Thanks for any help