Your pup is a HE dog, and right about now the male thing starts showing up. As Super Star said, its a dominance issue, and you need to get a handle on this quickly before it escalates.
You've already identified the growl when petting thing, so set it up, prepare yourself, and as soon as the first sign of a growl happens you need to roll him, raise your voice but good, and not let him get up until you're out of breath.
When you're done, put the food dish up where he can't reach reach it and ignore him for a bit. Put the food dish back, pet him again (fully prepared to roll him and holler some more), and repeat as necessary.
If it were me, I would continue to reinforce the thing for a couple of weeks, making sure you're petting him when he eats - not constantly, but moving around and getting your hand on him any time you choose.
The jumping is unacceptable behavior. What I have done is to use a friend or family member who understands what is about to happen, and let the dog do his thing. If your helper is a dog person, they do the correction - simple knee to the chest and and a "no". If needed, you follow up.
A rolled up newspaper is a great tool - the noise is impressive to the dog, but the paper itself doesn't hurt 'em. Just don't overdo things - use it only when needed, and its preferable to set up the situation so you're ready and waiting to make the correction.
Another thing you'll probably see soon - if you haven't already - is him grabbing yours or someone elses hand in his mouth. Its a common dominance thing for retrievers, and while it may be alarming for someone who's not ready, is pretty harmless. Roll him and let him know you don't approve. It will diminish within a few weeks.
Many years ago, I had a young chocolate lab (6 mos.) on a portage up off the Echo Trail, and we were on our way back from his first major duck expedition. Things had gone fairly well, and then we ran into a couple of hikers on the last portage.... The pup was going through some of the same dominance issues you describe, and upon seeing the couple, he charged up and grabbed the woman's glove - gently - but grabbed it nonetheless.
I come around the corner, see my pup with a strange woman's hand in his mouth, the guy was probably getting ready to shoot the pup, when I hit the whistle. The dog sits. He's still got he gloved hand, but sits. The woman says "what do I do?"
"Take your free hand, grab his ear and give a yank, and then yell "NO" and chase him"
God bless that woman, she did exactly what I asked her to do. The ear yank got the pup's attention - big time - she yelled NO and chased him. He rolled on his back, then crawled up to her, came to heel and kept nudging her leg.
I swear, that pup would have gone home with her after that!
They mean no harm at this stage - but if you don't catch the dominance issues and deal with them quickly, they can become a real problem later. Putting the pup away when company comes only puts the issue off - and harder to solve later. Avoiding touching him when he's eating only reinforces a bad behavior.
Give a few more specifics about the barking thing - when is he doing, what is happening when it starts. Usually if you analyze the situation you can set up a correction.
They're a lot of fun Northerngal - but a lot of work goes into making them good citizens and family members.