The barred cockerels came from.. either barred or cuckoo hens (Rock, Dominique, non feather legged Marans but doubt this one and doubt cram Legbar)... if crossed to solid color male, will throw sex linked chicks with males having a white dot on their heads at hatch and growing out barred and females being solid. If you contact the seller and ask which breed they have we could probably help narrow down the possibilities a bit more for ya.
No, that black one is not a purebred Australorp as noted by the incorrect comb. Can't see his face well, but agree possible EE. How fun to see them in the snow!
That's great, and then you will be sharing YOUR experience to help others as well!
Adding your general location can help folks make their best suggestions possible at a glance in the future.