Hey! I've personally never had trouble mixing younger groups with older ones. But it really depends on the behavior of the older group. I would recommend doing it at night. Also its normal for them to establish a pecking order so unless they are violently attacking the younger chicks I wouldn't...
Great! There was another thread about this kind of thing and they suggested switching them to game bird feed, because it is higher in protein. Hoping for a fast recovery!
Hey! It really depends, if your frizzle is the only one in the flock with feathered legs then yes, but if any of the other OE or EE have the trait then it might be some other OE or EE.
I think that the problem should sort itself out if she is eating on her own. As for what you can do, I would recommend adding some electrolytes and vitamins to the water to help her along with the recovery process.
Hey! I don't think I would be able to give you an answer for exactly how long until he loses interest in the chicks. But I have found cats tend to still show some interest in adult hens. I have not yet had a problem with any of them attacking the chickens, but I try my best to keep them...