Thanks for stopping by! I'll address your two question one at a time, but probably not to your satisfaction...
The way that human brains actually accomplishes its tasks is something which I want to completely black-box. Instead, my efforts are to focus on what the tasks of a neural structure are in the first place - regardless of how our species has evolved to accomplish them. In other words, I don't want to rule out the possibility of fully intelligent organisms that might be out there, but do NOT have a centralized neural system that we would call a brain.
Natural selection is differential replication under conditions of scarcity. This is all I mean by the "logic" of adaptation - that due to entropy, if a complex structure must survive for long, it must replicate (either a part or the whole of) itself in order to do so. Indeed, this idea is the only thing that separated Darwin's theory of evolution from all the other evolutionists that had come before him: he shows how evolution is not random or haphazard, but had a very specific logic that structured it.
Your question here is very much related to the debates surrounding "adaptationism" - a debate in which I definitely side with Dennett. Here's his flagship article on the topic: http://hdl.handle.net/10427/57584
Unfortunately, I probably won't directly address the Darwinian questions anytime in the near future... But who knows for sure?
RE: Introduceyourself - Paradigms Lost: A Genealogical Synthesis of Darwinism, Praxeology and Pragmatism