Thank you all for your answers, very helpful!
I certainly understand that every puppy involves a lot of work and effort, that's not what I'm worried about. I should probably have been clearer about what I meant in my opening post: the stories that concern me are the ones where people are completely exhausted, have tried everything to correct really unacceptable behavior, nothing works and their puppy is still "a terror" or similar words they use to describe the situation. I guess I wonder how common those situations are?
There were some questions about our situation etc, I'll try to answer those as best I can:
We chose to contact the breeder where Buddy came from because he's a great dog and also because we have heard a lot of good stuff about other dogs she has delivered over the years (she's a semi-local breeder, same county as us).
We certainly can commit time to a new puppy and we can exercise him daily. Buddy gets four walks a day and we play with him several times during the day. We plan on taking him to puppy class, I know that there`s a trained woman that hold those here sometimes. But that is of the 6 nights and then done variety, we don't have puppy daycare, ongoing, indefinite training classes and things like that here in rural Norway. There might be something in Oslo and other big cities, but those are all many hours away from our little island.
I've always wanted to visit Norway, but we didn't make it over when we lived in Scotland for a few years. Having a pregnant wife and a newborn will prevent that right?
It sounds like you are on the right track to avoid what you call nightmare scenarios, but as was mentioned above, you can attempt to stack the odds in your favor in every way and sometimes the chips fall in a difficult place. You have the best opportunity to avoid those types of situations through a great breeder, exercise, and early, proper, and consistent training. Many (not all) behavior disorders develop from poor foundation training and socializing during the early phases of the pups life. If, you get the pup at 8 weeks, those next 8 weeks are vitally important to the rest of the dog's life. Ian Dunbar's books on puppies speak about that period with a high sense of urgency as do most of the other current literature on raising, training, and socializing pups.
If, you don't have training classes available past the puppy stage, there are an infinite number of books and websites out there that can help you work with your dog. What you won't get with books or the internet is the social interaction and distraction level of a class, but you could socialize with other well behaved dogs and find other places with distractions to train after your dog has a behavior down to "proof" it and make it work with lots of different stimuli. The other thing you won't get without a trainer is the one to one help if there are training or behavior issues; hopefully the trainer you speak of could help in those situations or in the worse case scenario, you could find someone that does internet consultations.
Good luck and let us know what you decide!