Hi and congrats on your new pup. Sounds like a perfect match for your family!
No one can say for sure just going off a few pics, but he looks like he is American lines to me, judging by his short coat, big huge ears (he will grow into them), and his more refined head and muzzle.
He seems to be at a good weight from the pics - keeping track of how much he weighs as he grows is fun, but the best way to know if he is of good weight is to look at his condition - every dog is different, and every pup develops at a different rate, so just going by a number doesn't mean much. Some dogs lag behind then catch up, some dogs put on weight at a steady pace, others go through growth spurts, etc . . .
He seems just fine in the pics - watch that he does not fill out to much, or does not loose too much weight - if he does, adjust his food accordingly.
I bet this pup just thought he died and went to heaven going from a chain to a normal, happy, family life.