Ordinarily, I'd think the nipping was herding behaviour, but since Simon's a Labradoodle, there shouldn't be any herding instincts, so I'm going to go on the premise that this is a playing/pay attention to me behaviour, maybe with a little "I'm growing up and I'm going to see just how bossy I can be" mixed in.
Has Simon been neutered yet?
Keep in mind, too, that Poodles are a very curious breed. They want to see everything and know everything that's going on all the time.
It sounds like Simon needs some basic obedience training, especially "Sit." When he stands up to pilfer on the counters, tell him to Sit. He can't be up high enough to counter-surf when he's sitting!
Start working on the recall: I prefer a halter to a choker - I'd much rather not have my dog associate something unpleasant with being called! When you have him back at your side, give him "Sit" and when he's done that and held it for 10 seconds of so, lots and lots of attention - pets, hugs, whatever he likes best. Make it an attention party!
You'll need to keep some chew toys and whenever he bites, tell him to Stop or whatever command you want him to associate with not biting. (I don't recommend using "Don't bite" as someone who overheard you saying that to him might misconstrue and assume that you have an aggressive dog.) Then give him something that he's allowed to chew on. If you need to use the Sit command to get him to stop, use it. Sometimes that's the best thing to get a dog's attention.
Bimmer used to like to sneak up behind me and nip me on the butt when he was a puppy. He grew out of it after he was about 9 months old. Gotta admit, I kind of miss how much fun he had . . .