Best seller list?

Question for those of you "in-the-know".

What is the criteria for a book to make the NYT Best Sellers list and what is a typical first printing for a book?

We were talking about Clinton getting $12million advance and we were trying to figure out how many books they'd have to sell before they start making their money back.

I know that he will sell quite a few over the years but it makes you wonder how the publishers plan this kind of thing.