While I don't have any personal experience with EPIK (or JET or GEPIK) I would recommend doing a search over at the forums at Dave's ESL Cafe - Korea http://forums.eslcafe.com/korea
Specifically, I would do a search under the "Job-related discussion forum". I remember seeing a multitude of posts regarding EPIK in general.
Another source is from the horse's mouth - EPIK's homepage http://epik.niied.go.kr
but I'm sure you've already perused their official site.
By the way, 영어 너무 잘하는 것 같아요!