Yes. Brad Pitt has a brother, Doug, and a sister Julie.
Yes. Sig Chi
No even though they share last names.
In the first pic as you scroll down, the guy beside Brad is Doug Pitt, his brother: http://www.brangelinaenespanol.com/2008/03/que-se-siente-al-ser-el-hermano-de-una.html
No, he has a brother Doug and a sister Julie Neal.