[fostermom]

This is just my two cents but here goes.
My son had our old family golden, Toby. They were devoted to each other so there was never any debate about who Toby would live with. When Toby died (of old age) John wanted to get another dog. I tried my best to talk him into an adult but he wanted a PUPPY. He had grown up in a multiple dog home, even gone to obedience training with Toby (although John acknowledges I already had Toby trained so it was pretty much a cake walk for him). So John had dogs before, but he didn't have much background in training a dog (which sounds pretty much what your background currently is).
We researched golden breeders...we talked to the breeder and made it clear this would be the first dog he had to raise/train and we wanted an "easy" dog. Riley came into John's life at seven weeks. Pretty soon I was getting calls about Riley biting when they tried to correct her, Riley pulling on the leash so hard they can't walk her, Riley not listening, Riley chewing electric cords. John was WAY over his head with this dog. Riley is now almost two years old. She's improved in many ways but is still a handful.
And this is a golden...now let's talk ROTTWEILERS.
Rottweilers are large, working breed dogs. They have minds of their own. They are capable of making decisions about how the house should be run if you don't make the "rules" clear to them. I went from living with goldens to living with rottweilers and didn't have a problem. But I had done an enormous amount of obedience training with my goldens so had a pretty good grasp on what was necessary to end up with an obedient, well mannered dog. If I had a family looking to adopt one of my foster rotts with your background, I'd STRONGLY recommend getting an adult first...one that was pretty much bomb proof. Use that dog to learn about rotti's and then consider a puppy for your next dog. A rotti can demonstrate a strong-willed mind of his own, requiring a confident owner who can take charge...maybe not the best choice for a newbie.
You might get a pup that is maleable or you might get one who is quite a challenge. You might get one that is fine with the ferret or you might get one that is highly small critter aggressive. With an adult, what you see is what you get. My current (rotti/shep) foster recently had a close encounter with a one pound pup that was running down the aisle at our local pet store..the pup ended up between Rocky's front legs and Rock just gave it a casual sniff. He's hugely social, dog and cat friendly, no "issues"...the type of "easy" dog my son needed. He would be a great dog for a novice home.
I had a family inquiring about one of my fosters. They ultimately went out and bought a pup...six months later I get an email from them asking if I can take the pup...it was too much for them to handle. Nice family, great home for a dog, but just not experienced enough to deal with this pup. I would just hate to see you get over your head with a pup that needs a more exerienced owner than you currently are.
Again, just my opinion. Best of luck in whatever you decide.