I have been going to OBX for about 13 years now, almost every year.
Places to eat:
Mako Mikes ( only place that serves shark) ( also have a great crab leg special)
Blue Point ( great spot for lunch on the sound side, fish tacos are the best)
Red sky café
Duck deli is a must for lunch. I would go before or after 12 as its a big tourist spot.
Black pelican ( great date night, a little more costly but the seafood is great. Try the choc cake, its plenty big to split)
Duck doughnuts are great, its like a chipotle for doughnuts. You go in, they make your doughnuts in front of you and you get to choose your toppings.
Shopping is plentiful, there are some cool shops in the northern part near duck. Theres a small little winery owned by an Italian man. He has the best cannoli's I have ever tried. I cant think of the shop off the top of my head.
If you plan on doing any pier fishing check out the avon pier. It is the largest. Get there early as the end of the pier gets busy around 7-8pm.
There are a few local bars but not many, fish bones is a cool spot as is barefoot Bernie and lucky 12 tavern.
Take a trip down to cape hateras and climb the light house. Its a cool experience and a great drive through very remote areas along the island.
Most people don't take the time to explore, you can find a lot of hidden gems.