Win or lose, it seems most of my games are really decided about move 5-10, in the late opening and almost always outside a conventional book line. I've learned the basics to alot of openings, but learning those lines doesn't ever seem to lead to an advantage, just how to keep things even.

 

Are there articles or books about opening where there are examples of "Here's a common digression / mistake and here's how to punish it?" Because that seems to be where my games are decided.

Check out either (or both) of two books by Bruce Pandolfini: The Winning Way and Chess Openings: Traps and Zaps. Both focus on exactly what you're talking about, i.e., tactics in opening play that convert into strategic advantages. That would be my recommendation.