Big Al - can't help you much with Carolina Beach as I've only used it only a couple of times as a back-up re-entry location when the wind is such that I was getting beat-up heading north so I took the ICW back home. However I use New Topsail Inlet all the time.
NTI like many shallow draft inlets tends to shift around so always use caution. It is well marked by Coast Guard maintained buoys, but again use caution. The buoys are generally in the right places but sometimes they come loose. At low tide is about 7 feet at it shallowest spot (center of channel). I'd recommend you go out/come in with someone who knows the channels the first time or two.
It can get a little tricky on sloppy weather days so be sure to get familiar with it on nicer days. With that said, so far I've always been able to get back in there. However, I keep as a backup plan coming in through Masonboro if I ever get caught in real bad conditions (low vis, high wind, big seas). I would never come back in Rich's inlet in sloppy conditions - there is only 4 foot of water on low tide, it is not marked with buoys and is very, very hard to read from the ocean side if there is anything over 2-3 foot seas.
Hope this helps. I'd be happy to buddy boat with you sometime if you want.