If you have a 4WD you can go to Freeman Park (north end of island) and drive to the inlet, but you need a beach pass. There is also a State Park just behind the Food Lion as you cross over the bridge onto the island that you can hike and fish from the shore and another park on River Rd on the Wilmington side. You might want to stop in and talk to the folks at Island Tackle as they know the island fishery as well as anyone. Good luck!
Depends on how big the kids are.
The wall can be a dangerous place. It's slick in places, uneven, and gapped up.
Don't venture too far and you'll be alright. An incoming tide can leave you stranded real fast. Especially with a high tidal coefficient.
You slip and fall off that wall you are in for a world of hurt between the oyster shells and the rocks.
Carry plenty of rigs or rig making supplies. You'll lose some or a lot. Depends on how or what you are fishing with.
A good place on the beach is to park in the parking lot on the beach side of Fort Fisher. Walk north along the paved cart path. there is a small beach there. All along there is good sand bar but for flounder I would fish at the far north end where the natural rock outcropping goes out into the ocean. Those rocks hold bait which draws the bigger fish. Get lucky and you may tie into a tarpon.