Not sure if Brian got off at the time or later on, but he definitely enjoyed himself =)

Jon is mostly sub, but has his switchy moments. Stephen may have been able to pull off dom drag at the DMV; low-level government functionaries are not known for their careful attention to detail. He may have tried to pull off a few relationships with subs, although they can't have been much fun for anyone involved. (Even a gay or bi sub would still be frustrated by his denial and closetedness.)

Don't know about subs in general - it would depend on the individual - but Stephen has a thing for sleeping in his collar. It makes him feel more secure and protected.