Hi there,
https://en.bitcoin.it/wiki/P2Pool explains most of it.
Note that where it says local, that refers to Bitvolcano as a whole, not your mining.
Global refers to the entire P2Pool, those things confused me at first.
In other news, sorry for the outages in the last few days.
The p2pool software for YAC has become a bit of a memory hog over the last few days.
I've rebooted the server for now and I'm on the hunt for a proper solution.