BCS national title game?

I am a huge fan of college football. USC in particular. I've been watching it for quite a while now but still have some questions in just how things work. My main question is, why is Texas getting a chance to have a split national title if they win and not any other team? They not the only 1 loss team. Also i noticed every four years the national title game is at the Rose Bowl. some info on that about location?