Details on threading?

Beside a little example showing one can call Tracking and SubmitFrame in different threads, the documentation tells very little about threading. I have two simple questions:

1. Does the ovr_submitFrame have to occur in the same thread the SwapTextureSets were created in?
2. If no (runs at least for a few frames), does access to SwapTextureSets have to be protect against concurrent access for writing to them and calling ovr_submitFrame? (because it crashes after short period of time)