Finny sounds like a typical puppy. The "scruffing" as you call it is not teaching him how to behave.And neither will the smack on the nose. You need to redirect him to a more appropriate behavior. Try sticking a toy in his mouth when he starts biting. And when he starts playing with or biting on the toy praise him. This will help teach him to bite or chew his toys rather than you. If he will not bite/play with the toy ignore him until he has stopped biting.Walk away or whatever it takes to ignore his bad behavior. Then when he does stop biting praise and or give him a treat.To correct a behavior you have to show the behavior you expect rather than what you don't expect of him.This will take some time to teach. Please be patient and consistent.
Also training classes would be great. This will help you teach your dog commands (among other things) which will help you tremendously with correcting unappropriate behavior.

Angie