Sometimes there's a hormone imbalance that causes hens to develop roo-ish looks and behavior. I'm not a expert on this, so I'll be learning right along with you :p
Yeah. I'm going by comb and sometimes posture. They seem a bit young right now, so I would hold out for longer. Sometimes they pull the ol-switcharoo. It seems pretty amazing to get that many cockerels.
It looks like a cockerel to me, but it's somewhat harder to sex orpingtons. It's probably best to wait it out. I would cry if I had to give a lavender orp away :hit