Yeah, he looks absolutely petrified. Think of it as Munch's "The Scream," revisited. (But I'll bet he was just doing that for the benefit of the camera, that he really didn't mind Karen's foot on his shoulder.)
Well, yes, that would have looked a little unusual - a group of adults lying on their backs on a dolly with their arms up in the air. But I'll bet they had a lot of interested spectators.
Good question - Richard's puppets are usually the ones doing the famous head tilt, so it could be him.