We have just one ferret now, an old boy who is almost 8. Sadly his litter brother and lifetime companion died just before Christmas. We also have cats and dogs, but we can't allow them to mix as the dogs would go for the ferrets and the ferrets chase the cats.
My advice would be to get two ferrets at least, as they keep each other company and play together. Also, get them young - at about 8 weeks - as it's much easier at that age to train them not to nip, and make sure they have been well handled. Ours were about 16 weeks when we got them and have always been a bit nippy. Ferrets have very sharp teeth and their bites can really hurt I have plenty of scars to prove it If they decide to fasten on to you with their teeth, persuading them to let go isn't always easy.
Ferrets are cute little creatures that behave like playful kittens who never grow up. They stay playful even into old age. They are very entertaining to watch, and they are very clever. DS often walks around with his ferret draped round his neck like a furry scarf, and sometimes takes him for a walk on a harness which it takes at least two people to get on
They do smell, there's no doubt about it. It's a sort of warm, musky smell that some people like but most people IME don't. Our boys are neutered, which reduces the smell somewhat, but no way could I have them living in the house even though I don't mind the smell personally.
Ours live in a very large outdoor hutch, built by DH & the DSes and known as Ferrety Towers. Plus they have a secure run in the garden that they can exercise in. Ferrets are extreme escape artists. Several times ours have dug their way out of the hutch and let themselves into the house through the cat flap! Or they've wandered off through the garden and taken up residence under the shed. Luckily they come back when called and seem to know their names.
They use a litter tray in their run, and when they come into the house for a play they always use the same corner of the kitchen as a toilet so we put newspaper down there.
They eat kibbled ferret food, but dry cat food is OK in an emergency, and use the same water bottles as rabbits & other small pets.
They need their claws clipping regularly and we found that if we put a drop of cod liver oil on their belly we could do it without being shredded.
Sorry for the essay, hope at least some of it is useful!