I've got 3 black copper marans that are 5 weeks old - and two of them already have combs larger than those in any of your photos. So I would say there is hope that you have some pullets.
Here's what I think..
1- Cockerel
2- I'm not sure yet. (could you take another picture that shows a close-up of the face?)
3- Cockerel
4- Cockerel
5- Pullet
6- Cockerel
I still say all boys. If they are only 8 weeks old and their combs are that red, they are most definitely cockerels, not to mention the wattles already coming in
I know it's probably wishful thinking but I decided to take another set of pics in better light to see what you all think, Their combs are mostly lite pink and I looked up on my records and they were born the last day of November.