My daughter & son-in-law are currently in Beaufort, SC (aka the off-base military housing for Parris Island, US Marine Corps). What do you want to know? Both my wife and I have been down there (7 hour drive from Richmond, straight down 95) many times.

December? Ontario, Canada vs southern SC/GA seacoast border. Okay....
No snow.
No alligators (they migrate further south to warmer waters).
The best activity would either be waterfowling, or salt water fishing off the piers.