Your puppies teeth are hurting them that's why they are constantly teething. Sooth their teeth with a frozen carrot.
Puppies don't know what "NO" means but they can learn by teaching them the right thing to do. Say "NO" when your puppy is doing something you want them to stop, then reward them immediately when they eventually stop.
Dogs love to work... that's why your puppy is gnawing at your furniture. Stimulate their brain by giving them a puppy puzzle or brain game.
The crate is a game changers for raising a puppy. It helps them get their essential naps in without interruptions.
This is super important from the start. Seclude an area of your home just for them. Don't get give them full reign of your home or else you will have behavioral issues.