I'd like to add on what Rob said for #1. It should actually say:
1. "Pay a programmer a lot of money to create one for you.
It took thousands of man-hours and millions of dollars to make Facebook what it is today. It is more than just scripting, but also marketing, psychology, and legal. It is an extremely involved task.
But by all means go for it if you want to. Don't let us discourage you, just make sure you count of the cost before you build the tower.