CLT Westin end March
Good oysters and seafood aren't plentiful in Charlotte, I'm sorry to say, and probably least of all downtown near where you will be staying.
Georges Brasserie in the Southpark area has a nice selection of oysters and some fish dishes, nothing really local, if that's what you're looking for.
Customshop is a short cab ride for you and has great cheeses, charcuterie and I pretty much love their entire menu. They always have a lovely crudo dish and they often get in NC/SC fish. http://customshopfood.com/menu.html
5Church would also meet your food requests, minus the oysters. http://5church.com/ (this is downtown).
We have a new restaurant downtown (adjacent to The Dunhill Hotel) called The Asbury that I haven't yet been to but seems to meet all of your needs - southern inspired menu, oysters, house-cured charcuterie, etc. http://www.theasbury.com/
I'm sure others will chime in. Enjoy your visit!