Not sure on the tickets to get in, but you HAVE to go through some proxy in Korea who will get you the tickets. And that DOES cost money. If you do have time while there, then definitely try and see one of the shows, but just be advised that you'll be there the entire day.
Either that, or you can check out KARA's schedule and try to plan to be at an event that they were in. That's why I did and it was a lot cheaper. =D