Talent, determination and personal connection. If someone doesn't have all three, they're not a good match.

For cofounders an even equity split is the norm unless one founder brings some particular extra value. but no hard-and-fast rule really, basically just find a split that everyone agrees on.

For early employees see Fred Wilson article: http://www.avc.com/a_vc/2010/11/employee-equity-how-much.htm...