It must be in the docs somewhere, I didn't see it: The social platform: What does it host, or is it only a peer-to-peer matchmaking service? If it hosts 'stuff', what 'stuff'? Scenes, avatar models, textures, sounds, other data, etc? If anything is hosted, is it encrypted, or in any case, how secure is it? If nothing is hosted, what are best practices in sharing such content? Is video streaming supported? From cameras, screen-shares, VR cams, etc.? Is anything recorded, if so, by whom and for how long and who has access to it?
The Platform SDK doesn't host game servers for you, it's more like a middleman server system (and collection of libraries) for things like Matchmaking, Friend Invites, VOIP, Leaderboards, Achievements, etc
HOWEVER, there actually is a cloud storage feature so you can store that sort of stuff yourself if you need to (per user, not per app though- it's mainly meant for things like cloud saves).
As for Avatars specifically though, there is an Oculus Avatar system that it's highly recommended to use. Users edit their Avatar in Oculus Home and it is then consistent across all apps. It's also first person so it gives you hands for free.