Absolutely start with obedience classes. That will be the most beneficial thing for you both. They will teach you how to deal with a lot of the behaviors you don't like. In my opinion, a dog that age should know a lot more than sit and down without the need for food. You will both build a strong bond and trust in obedience training. I am a strong believer in that. Find a reputable trainer that uses a mix between positive reinforcement as well as corrections - that is the advice I give everyone.
Personally, I don't allow dogs to touch me anywhere with their teeth. I consider that to be unacceptable, regardless if it is affection, or play. I may consider it to be play, but a child or a stranger won't think the same thing, so I just don't allow it. You can yelp, and curl up and cry and walk away and ignore - these all work. Personally, I jowl pinch. Only you can show the dog what is acceptable and what is not acceptable to you. The dog won't know and "grow out of things" if they are never shown differently. This is why I always recommend obedience classes. Not only will it show you how to train your pup, but it will also give you an opportunity to speak to your trainer about certain things you want to change and how to address different issues.
In my opinion - I don't play tug of war. Tug of war with your dog exercises the dogs jaw muscles, it exercises head shaking, it exercises the dogs ability to growl, it teaches them that if they try hard enough, they can take things away from you. I am not saying it is bad for a dog. There is nothing wrong with playing tug with a dog...however, I don't recommend playing tug until you have a strong relationship with your dog and the groundwork of obedience is understood. I wouldn't play tug with a dog that also hasn't learnt that teeth on skin is not allowed - if a dog is playing tug and begins losing "grip" with their mouth, they will re-grip and can possibly bite down on your hand without meaning to. A dog that hasn't been taught this yet, I wouldn't play tug with. To a dog at this stage, they don't associate a certain toy with tug, they think that everything is a game and everything can be a tug game. When you let go and the dog takes what he/she is tugging, to the dog they just "won" the game. The especially love it if they take something away from you, win in a game of tug and then you chase them around until you can catch them and take it away. This is a dogs favorite game.
In my opinion, I wouldn't play tug until you have taught the dog that you are in charge...when you can initiate a game of tug, and they say "okay done" and the dog releases immediately and leaves the toy alone and the game ends. Tug isn't like playing fetch. It's fun to watch and its funny to see them try to win, but it's also a predatory behavior, to bite, hold on, head shake etc.
I know with police dogs that I have been able to work with, when they play tug games as a reward for good work, they let the dog play tug, and then call them off of the tug. That tug gets put away and the dog is not allowed to use it or play with it until their handler initiates the tug game during a training or working session. These are dogs that are trained in bite work and their release commands need to be perfect at all times.