These are still very young, and it is difficult to tell leg color in the pictures.
1. It could be an off colored cuckoo Marans, but I think olive egger or Lakeside egger is more likely.
2. I can't tell leg color just yet. If they are white, then probably a speckled Sussex. If they're yellow, then a Welsumer or brown Leghorn.
3. Probably a New Hampshire, which they list, or a Rhode Island red.
4. Same thoughts as for the first one.
5. I agree with buff Orpington.
So there's going to be some uncertainty for a while longer. With 1 and 4 you may not know until you see the color of their eggs. Best to start determining gender at 6 weeks or later unless you see a big raised comb before that time.