Tranaction type for PayPal Website Pro

Hello,

I need a bit of a help with selecting proper transaction type with PayPal's Website Payment Pro. I have two options - "Sale" and "Authorize and Capture". I understand the difference between two, but I'm not really sure what will need to be done if I choose "Authorize and Capture" option. How would I be able to finalize the transaction at a later time?

Also, I've been told that "Authorize and Capture" is really the only legal way to go - i.e by the law, I'm required to first ship the item and only then charge the money. Is this true or I can safeli use the "Sale" method.

Thanks!