Well she was sick as a newborn and I nursed her back to health, so I think she is just a bit behind (I think she is a girl though). Also Orphingtons are a giant breed. My inclination is that the black Orphington is a cockeral as he holds himself differently and has pointy tail feathers, but that the white and blue orphington are pullets too (they do have some red wattle but round feathers and fat bodies).
It's hard to say... it was easy to tell with my buff Orpington's because they were all 6 are one colour and the differences were obvious.
I do agree about the black one for sure, it's hard to say from the picture about the others.