The puppy should not have been treated this way and you were right in finding it a new home. Dog training requires being firm and consistent but not screaming and slapping a puppy around. First and foremost training requires patience and making a puppy feel secure in its surroundings .
Besides a mutt as a kid also, I've only had chihuahuas (I'm on my third one). I'd like to get a different breed but afraid of what I may be in for so I stay with what I know, even though within the same breed there are lots of differences in personality and temperament.
I think if you have to ask then you should not be breeding dogs. In my opinion you are not being a responsible dog owner. Dogs should not be bred on a whim, which is the impression your post is giving me.