Bit hard to tell from the photos but the white looks like it might be a hen, the second pic looks like it is going to be a rooster. It has the larger flaps (forgotten what you call them) under the chin. The one standing next to the white one in the last pic also looks like a rooster for the same reason.
Are pic 1 and two the same bird? pic 2 is a rooster, im pretty sure since the wattles and comb are comparitivley larger than the white hens. the black bird is also a rooster, tail feathers and the combs and wattle are a good indication of sex, the chick in the very last picture is at an age where it could be sexed also.
Well after great deliberation LOL (just went into the chook house and baled up a hen) the black one next to the white one is a rooster and the white one a hen and to me the middle pic is a hen. My silkie girls have the wattles and a big buffy topknot. You really never know until they start crowing. I wait until crowing until I sex them. They are good look silkies.
The black roo may not be completley pure, hence the red skin, pure silkies should have black skin but it doesent really matter if you not showing them and he could be majority pure just a cross may have been made a while back. and will still make a great little roo:)
Pic 2 definetly a rooster! and the black one definetly a rooster! as for the others cant see their combs so cant tell!! although i have had a couple roosters that looked exactley like hens! they had really small combs, but they where crowing so they soon went! and i didnt want to breed with them!