First off, welcome to YT and congrats on your new addition.
Unfortunately...for you
and poor Matt...the best way for him to get used to the harness (which, kudos, it's much better than a collar) is to continue with what you are doing....same with the walking. Eventually he will quit resisting and realize that's just the way it has to be.
In regards to the biting...you need to put a stop to that now. Generally speaking, 8 weeks is waaaay too young for a pup to have been placed in it's forever loving home...most respected breeders agree that around 12 weeks is the best minimum age for placement. Learning to not bite is one of the behaviors that dogs learn by staying with the mom and littermates during that time frame. Definately make it known to your little guy that biting is not acceptable and be consistant with trying to stop the behavior. Definately not something you want him to continue doing.