Brewology

I believe the addon content is saved to you system and not to the games save. However, if they also have the content and use your save then data pertaining to that content will be available. I don't know for sure but that seems to be logical.

no, it wouldn't be, it saves to the network, and has a backup on your system and memory card, if you gave someone your memory card, I'm sure it'd be on there.