Based upon feathering, looks like 2 cockerels and 2 pullets, (one blue cockerel, one splash cockerel). RE: Vulture hocks. At 3 weeks I'd say it's too early to tell. The hocks are one of the first places that Cochins start to feather out. I'd be more concerned at this point about what appears to be (from the one photo) bare middle toes. Maybe there's some fuzz there? Then again if you just got them to run around and look good and don't intend to show them, they'll be fine.