The settee on the port side can be used as a birth but the one on the starboard side is much smaller. Two people can sit on it comfortably but not laydown. My wife will kind of half lay in it sometimes when we are watching the TV.
I recommend you repost this in the C310 group section. Someone there might be able to give you actual dimensions and we would be more likelly to see any other questions you have there.
Fair winds,
Jesse