It sounds like you've heard of most of the acronyms, so what is it you think you're missing. ~90% of ad buys are auctioned CPC or reservation CPM. Direct and exchanges "big deals" but most ad startups attempt to optimize a component (in Google this kind of image: http://www.cogmap.com/blog/wp-content/uploads/2010/10/LUMA-D... was a classic "explanation" of the ads ecosystem). As you can see, serving is a small part, and the majority of that ecosystem works on reservation CPM or bid CPM.
My question to you is, if you know these tehnologies, what is your actual question (other than coming to grips with the complexity).
Maybe most people just use dfp but I'm guessing that a number of publishing oriented startups and new businesses are having to learn and grapple with this stuff - was hoping to learn a bit from the collective