Douglas and the ferrets get along great. Ferrets are curious, intelligent animals easily capable of really hurting a dog, though. Neither of mine would, they think they ARE dogs, unless they were defending themselves.
Most ferrets are okay with dogs but it does depend on the individual. The dog also has to be trusted with the weasels which is easier said than done sometimes. Once they get along they are the best of friends, at least around here.
They eat meat. They are obligate carnivores, and are fed as such. Organ, muscle, bone, etc. Fairly similar to with a dog I think, except they are a lot more violent with their food. It's somewhat scary sometimes to see them fight over a choice piece of meat. They have huge teeth and jaws capable of crushing the bones in my fingers, and they hiss and screech when they are unhappy.
They have never hurt anyone though, Thatcher was a biter when I saved him, I intended to have only one ferret but the rescuer in me had to save his life. He loves kisses now.
They are wonderful pets, very affectionate and cuddly, they love me more than anything and smother me in kisses. Bode is a service animal as well. If you have what it takes to keep them I highly, highly recommend them as one of the most wonderful pets I have ever owned. They are my angels even if they can be brats and they love Douglas also.