I think they probably are all pullets.
You might be right about the breed.
That bird should be a pullet. The salmon color in the breast is a female-specific trait for chickens with that overall coloring. A male would have a black breast at that age.
I feel that the color is not right for a Bielefelder, but it should be a pullet anyway because of the breast color (salmon-colored breast, not black breast or even another shade of brown.)
Now that one looks more like a Bielefelder. I think you have #2 and #3 breeds swapped. This one also looks like a pullet, again because of the breast color, but also because of the comb being small and pale.
(Note: of course not every breed can be sexed by breast color at this age. But you have a whole clump that can.)
I think that looks like female coloring, but I'm not entirely positive. Mypetchicken does not seem to have whole-body photos of a male, and I'm not having much luck finding them elsewhere either. But the description on mypetchicken does make me think a male should have a black breast and a lot more black in other places.
Some breeds have very big combs at maturity (including Leghorns and Penedesencas), and the chicks of those breeds can have larger combs than the chicks of some other breeds. Yours definitely has a pale-colored comb and wattles (where a cockerel would probably have a brighter pink or red comb & wattles by now.)
I think you are probably right on both counts.
Based on the comb and wattles (small and pale), I agree about probably pullet.
As for which kind it is, after looking at all the rest, I agree that is should be the Super Blue Egg Layer.
This one looks female to me (mainly comb & wattles, but the color/pattern "look" female to me too. I've been fooled before by birds that "look" female to me, so I'm glad to have comb & wattles as an extra check.)
Considering the feathered feet, I agree this is probably the Green Queen.
Looks female to me, and I agree about this one being a Silver Spangled Hamburg. They're pretty distinctive
I agree about Exchequer Leghorn, another nice distinctive breed.
Looking at the comb and wattles, they are a little on the big side, but are still nice and pale. Since this is a Leghorn, I think this is just a case of a large-comb chicken breed, not a male. (Like a few of the others.)