I don't know if there is much of a split in Brittanies between field and show lines, but the ones I've seen that are used as gundogs are very full-on intelligent dogs who need some clear boundaries. They're an HPR breed - hunt point retrieve, and the 'hunt' comes first for a reason.
Puppies and cats: all of our puppies (we've had three) have learned the mantra Cat is King very early in their lives.
Puppies and kids: kids need to be taught to respect the puppy (let it eat and sleep in peace, never pick it up, never drag it around), to clear away their toys if they don't want them chewed, to put away their nice new sandals if they don't want them chewed, and to keep their hands away from puppy's mouth if they don't want them chewed either. IME the biggest problem if you have a puppy and young children is finding the child-free time to train the puppy properly.
Training is generally much more knackering for a dog than exercise. A long sit-stay in the middle of the playing field means my young dog has to really concentrate on NOT moving, and I swear 5-10 minutes of that wears her out more than twice the time romping about in the woods.
And yup, as PP have said, prices are mental at the moment, with even some fairly reputable breeders taking the piss a bit. That said, the really reputable breeders are charging what they always have: one I know with a litter of top-end working dogs is charging what she always does.