I'm raising a m/f pair of Faverolles right now, they're just at 6 weeks! I thought the same thing as you about the black, when their wingtips came in black at 1 week I thought they were both cockerels. But lo and behold, the 2nd row of feathers came in tan/brown and sure enough, she's a pullet! I was making guesses at 1 week, but I was completely certain at 2 weeks old.
as for temprament, they were really really flighty and timid as chicks but I have won them over with handfuls of ground oatmeal. they're very friendly now
I am raising them with 14 wyandottes who are 3 weeks younger. I hope that this will help to address pecking order issues by having the Favs at the top as the oldest. The little wyandottes seem to think the Favs are their parents, I swear they will even try to sleep under the pullet's breast. They copy everything she does as if she were a hen. I hope this makes for a fantastic broody mama when she's older! here are some pictures when they were little and I was trying to sex!
1 week old - see the black on the wings and the back? that is the PULLET! omg
2 weeks old - pullet
2 weeks - cockerel
when his hens come to me. our Barred Rock are very verbal hens as well. Brahma are fairly quiet as are the Legbar. Serama talk to our daughter but not much to me unless I call them late for dinner. 
I am wondering at the size of them. I just read that they are timid and can get picked on. I pray not! 
