Fantastic post TVB. Only item you didn't list was SPREAD which I believe is the # of blocks worth of work to pay out, ie the PPLNS window size (N being SPREAD # of blocks of work).
I will soon follow up with details about the /networks.py file which is not coin specific but p2pool specific and thus different from /bitcoin/networks.py!
/networks.py contains the SPREAD value etc.
Ah ok, right. Two different files with different purposes and exactly the same name.
One really should be coins.py.