Hello! Welcome to the site!! We have 2 Newfoundland puppies, our Bella is 11 months and Rocco is 11 weeks. Bella was quite easy to potty train, but our little Rocco has been a bit more challenging. What someone said above is true, make sure the crate is just big enough for them, but not spacious enough where they have "room" to go potty in the crate. With Rocco, he eats teice a day and I make sure I feed him by 4 or 5 pm, so that gives him time to digest and potty a few times before bed time as he sleeps in his crate for now. As for the biting, that's something that you'll want to tackle now as it could become a larger issue as the puppy grows and you don't want your sons injured by a biting dog, or have the dog bite others and other animals. Rocco is mouthing a lot, and what we did is this: we went for a private session with our trainer who we take Bella to for obedience class..our trainer suggested we do a tongue press, similiar to holding the pup's snout and saying "no bite". The key is to be consistent, and it does take a while to see improvement...
.but if you keep at it you will see progress being made. I think its great that you rescued one of the puppies from this litter. It makes me sad when I hear stories about animals being abused and beaten, even though I know it happens! Keep us posted on how things are going with your puppy