Definately take this pup to classes- puppy socialization classes typically are for dogs as young as yours and all are screened for having the appropriate shots for their age. Find one in the area and go to it.
Being "pack leader" absolutely does not mean being mean to the dog. It's consistent enforcement of the rules. Yet, in order to enforce the rules you first have to show the dog what the rules are. Do an Internet search for "Nothing in life is free- dogs" and you'll get a good idea how to be a pack leader without beign a bully.
As for your dog soming in the house, sitting comfortably and not marking- that too just involves training. TEACH the dog to go outside. Marking is no different than potty training. It's not tolerated in my house and I don't set my dog up to allow it to make mistakes. By that I mean, my dog earns freedom to wander the house without me present. Initially, he was tied to my belt on a 6' leash. Then, when he was good about that, he was allowed to be unleashed in the same room with me. Eventually, my bedroom and hallway. Gradually the rest of the house.
Neutering your dog will also help with marking. It doesn't eliminate th need to train the dog. If your dog is spending long hours in an outside kennel, housetraining is harder. There really is no substiute for putting the time and effort into training. No dog automatically knows how to be a good dog.
Your puppy will be great. You just need to make sure you are a great teacher as well.
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Chelle and the rest of the crew including, but not limited to Kita and Taiko (the shiba inu wrestle maniacs), Adi (reserved and dignified tabby cat), and all 28 reptiles www.freewebs.com/performanceshibas