Well, you asked.......
Allow your kids to pick him up, crawl all over him, sleep with him and roughhouse with him, as much as they want. With the exception of jumping up and putting his feet on them. Hard to break, once it begins and it is NEVER a good thing.
One of the most important things you HAVE to do is to establish his position in the family "pack" and that way, if you do not nut him, he will not have kid issues later, when testosterone kicks in and he wants to assert his authority.
Basic obedience training is a must also and there is NO age so early that those...or any... lessons cannot begin.
Go to a local trap club and get as close to the firing line as possible. In the parking lot, play with your pup while the guys are shooting. Ignore the noise and he will almost immediately ignore it also.
It helps if you have a friend with a seasoned dog to go along. Same with swimming. They learn things from the reaction and response of other dogs, much faster than humans can teach them.
I have taken a LOT of heat for that one, but I have broke several "gun shy" dogs, in just a few trips to the gun club.
One other thing, keep him in a kennel crate at night. If you start this early, you will never have issues with him when traveling.
Also.......NEVER HIT YOUR DOG WITH ANYTHING!!!!
You want him to love and respect you and your family, not fear you.
When the pup bites, or nips, you can roll his lips into his mouth and make him bite himself till he whines. He will stop the biting soon enough.
If you have a behaviour issue....and you will....pick a word, or a hiss sound and use it CONSISTANTLY whenever he does something you don't like. He will soon learn that you ain't happy when you use it and he will want to avoid hearing that.
"I could eat a bowl of Alphabet Soup and
sh!t a better argument than that!"