What does the P2P option in LoL do exactly?
Is it only used for patching/updating or is it also used for sharing match bandwidth to take a few bits of load off of Riots servers?
Is P2P sharing turned on only while one is at the patching/updating screen or does it also share some of your bandwidth while you are playing regardless of what it is used for?
If you mean the option in the launcher, yeah, it's just to download content faster.
While playing the netcode of LoL (or any other game for what i know) doesn't work as a P2P network, there's a host and a group of clients. Usually you never exchange datas with other players, because if the netcode should rely on that, it would be easier to hack the game.