"Better you than me" indicates that while you're happy for the other person, you're glad the situation is not happening to you. It's not something you want or are interested in.
"The boss invited me to go on a hunting trip with him this weekend."
"Well, better you than me. I can't bear the thought of spending the weekend in the woods. Have fun!"
"Way ahead of you there" means that you've already thought of a possible obstacle or outcome and have planned for it in advance.
"Oh, geez, my wife wants to go away on a romantic rendezvous this weekend for our anniversary, but that's the weekend of the big Michigan-Ohio football game!"
"Way ahead of you there, buddy. I've set my TiVo to record it for you, so you can watch it Monday night when you get home."