I'd sign up for an obedience class with him, just as a way of strengthening the bond between the two of you. Again, a harsh word is far more wounding than a physical blow to these big lugs, so keep that in mind. You might keep a leash on him for a time, just so you can easily lead him where you need him to go should he refuse to otherwise. And I wouldn't be too concerned about the kids with him, as long as they are well-bahaved with dogs. Saints usually treat kids like their own pups, wouldn't hurt them, and are often protective of them if stranger approach.