Hmmm... Well, 9 months is pretty old for a puppy to still not have learned bite inhibition. Has he spent much time with other dogs and puppies, especially when he was 8-16 weeks old? Puppies learn to use their mouth softly from playing with other dogs, as well as from you.

When his teeth touch your skin, you need to go into complete IGNORE mode. Either yelp loudly, or give a stern "Nooo!", and ignore. Each and every time he nips at you. Teach him to be gentle to your hands, by holding a handful of soft, tasty treats. Offer him your hand, and hold the treat between your fingers so that he can just barely nibble on it. The second he nibbles your finger, the treats go away. Wait a few minutes, and try again. He only gets the treats if he takes them gently.

Do not leave him out of his crate when he can't be supervised, at this age! He is teething and going through his rebellious stage... and he has obviously proven that he will chew things up. It's easier, and safer for him, to crate. Make sure he has PLENTY of safe chew toys, and make sure he knows they are appropriate to chew, but furniture/carpet isn't. This is "normal puppy behavior" per se... but do NOT expect him to just grow out of it. You DO need to do something, or you will have an unruly, ill-mannered adult dog on your hands. Puppies become polite adults not naturally, but through being taught what you expect of him.

Golden Retriever x Standard Poodle mixes are predisposed to be very active, very demanding dogs... just based on the activity levels and intelligence of both of those breeds. Make sure your pup gets lots of stimulating, vigorous exercise, and training sessions, every day! : ) Tiring out your puppy a few times a day, mentally and physically, is sure to help with the chewing and rambunctiousness as well.