Maybe Pekin Bantam has two left feet?
Feathering in quickly can be indicative of a pullet, but mine are all pretty much feathered in, so I'm not sure if it's reliable at this age.
No, I don't think they're all boys.
I have BLRW that are approximately the same age (hatched 2/6). I can see obvious hackles on a couple of them, and bigger combs than at least a couple of yours. I didn't feel like I got a real good look at your recent pictures so I couldn't say for sure...