Nothing great to eat within walking distance of OB. There are some bars, like Duffy's that have some fried seafood.
Locals love a place called Haskins on Main Street that is close. Breakfast and lunch are best. Always a line out the door but it moves quickly.
Driving wise, you have a 1000 choices. We love Boardwalk Billy's just off 17, Flying Fish at Barefoot. Tiny place called Rockefellers has good oysters on the half shell at about $.50 each during happy hour.
Have fun.