Yes you can use your fresh water gear, yes the salt water will corrode it.
Lube it up good before you go, rinse it off with fresh water after using it and it will be fine. Rinse the whole rod and reel. The pier will have a table with fresh water for you to dso this.
I would fish from the piers. The one you have noted is a good one because it is close to a small inlet that flushes food in and out daily with the tide. Also if you pay to fish a peir, you don’t need an additional license. I think you need a salt water license in SC to fish from the beach. That may have changed, check with the SC F&G webpage.
You do it just like any other kind of fishing, you can either still fish with bait or throw lures.
You will most likely catch things like Pompano, Spots and Croakers using shrimp for bait and fishing on the bottom using pyramid sinkers and a dropper rig. Stainless hooks are the norm. These fish like it in the surf zone, either right where waves are or just outside.
You can throw castmasters for Bluefish, macks or other faster, more agressive fish. Wou may experience a Bluefish attack where they swarm down the beach and you can catch several on castmasters as they pass the peir.
You will be interested to watch the guys who King fish, they will be using trolly rigs and congregate on the end of the peir. Some peirs only allow King fishers on the very end of the pier.
You probably don’t need to rent, that is something you can decide after you get there and check it all out. I would bring my longest bass rod, 7’ and a good spinning reel with 12 lb test or so, braid is nice for lures because it casts farther, pick up a spool of “Mason Mill Ends” at the pier shop as a leader in 30 lb test. Blues are toothy.
The pier will sell everything you need, but if you have some castmasters like used for stripers at powell bring them, also any white jigs like used at the Berry, leave the Rapala’s and other plugs at home, pier fishing is done from 20’ above the water and metal and lead work better. Yellow and pink are also good jig colors. Use the big ones you hardly ever get to use here. Twister tails and swim type baits are worth bringing along too.
I think the 2 hours before and after high tide are best, but when I lived in NC would spend entire days from 4am till midnight on the piers.
If you have the time and resources, I would also consider getting on a party boat, do a mid-week morning trip to avoid the crowds. Most party boats provide tackle and bait, bring lunch and some water and sodas.