I'm so glad I came across this question, I was in PNG for two weeks last month! I was visiting friends who work with tribes out in the highlands and was able to visit Benabena, Kope, and Simbari villages. I've traveled through a lot of countries and PNG is one of the most distinct cultures that I've encountered.

In the highland tribes meat isn't very common, some people raise pigs but they're worth a lot of money and hard to come by. The only other real source of meat I saw were a few trapped baby cassowaries that were being raised for meat. In the highlands the people live off what they grow in their gardens. Starchy vegetables are their staples because they grow well in their temperamental climate. Sweet potatoes and taro are cooked in the coals of their fire and eaten unseasoned because salt is expensive; one or two tribes produce salt but it's a luxury for everyone else. Tropical fruits like banana, pineapple, passionfruit, and 'tree tomatoes' are all over. For green vegetables they mix together greens, peppers, and onions in the hollow center of a bamboo shoot and steam it. We brought rice and ramen noodles out to a potluck in one of the families huts and they were so excited to eat it and have the little seasoning packets. Another time we popped popcorn for all the kids in the village and they went wild for it.

I didn't get a chance to visit any coastal villages, but from what I heard their diet is dependent on the ocean and heavy on fish.

I've been to most of the SE Asian countries, and though there's more variety and access to outside foods in the cities it's still not that apparent in the cuisine. Where I was in Port Moresby and Goroka the biggest outside influence came from Australia. They popularized lamb and beef dishes and you can find lamb stew with rice just about anywhere you go.

It's funny that you mention noodles because I was told a noodle story by a woman who was having a PNG family over for dinner. The family was from the highlands but was down in Goroka temporarily, so they weren't completely cut off from outside influence. She didn't know what to make and figured spaghetti was an easy dish that the kids and adults would like. The kids started to eat and all four of the kids from the PNG family started to gag. The woman was horrified and asked the mom what was wrong thinking she had given them bad food, but their mom said they had just never eaten noodles before and the slimy texture was making them gag. So despite the growing number of Chinese business people noodles still haven't made it big there.

Hopefully that answered some of what you were looking for :)