How to start a Legal file sharing website?

[wynn]

what legal information should i know before stating a sharing website?
i am an php programmer and i am thinking of starting a completely free downloading website ( sharing files ) like "rapidshare"

what do i need to know before i start making such a website and how to avoid becoming a criminal and making a complete legal website.

do i get sued if any of my users uploaded some illegal content ? will it matter if i made report abuse link below each content ? is it my responsibility ?

those information i need to know according to USA and international laws,