well... my hall (the kappa hall) is obsessed with SITC! my lovely roomie dawn has all the seasons on DVD and we watch constantly!
I am not sure about any key necklace, but yes indeed, charlotte was a kappa in the show. in season 2, her sisters visit, she tells them of her marital problems, and then they are referred to as "kappa kappa gramma" due to their opinions on her problems.... but it is really funny, we enjoy it!