I have a corkbark oak I am about to replant in a little bigger pot. I know they are evergreen trees and I need to know if it can stay outside thru the winter with roots protected from freezing or does it need inside.
Where are you in SC? Wikipedia says this about Q. suber: "In the area of distribution, the temperature rarely falls below freezing point, but temperatures down to −5 °C (23 °F) without damage and down to −10 °C (14 °F) without major damage can be tolerated."
I'd suspect it'd be fine, but I don't have direct experience with Q. suber.
(1) Is this a good time to transplant a Mediterranean species in South Carolina? No.
(2) Can you leave cork bark oaks outside year-round in South Carolina? Yes - I have several that I keep outside year-round in Charlotte, NC, and they have been doing great.