Here, have a soothing and yet relevant song:
Well, firstly, I haven't had an interview yet, so I can't talk from my own experience. But I can give tips on how to pass ANY job interview, based on what the successful applicants have said. [Edit: I passed my interview! So you can trust me after all.]
For ethical reasons, NO, I am not going to tell you what they might ask you. If you have come here looking for the questions so you can create rehearsed answers, stop reading now. It won't help you.
What I will give you is general advice that has been common to most responses to the frantic questions of 'What do they want from me?!'
This is not doctrine. Hell, I don't even know if this is right, because I haven't had my interview yet. But this is basic common sense as far as interviews go, for any job.
Here we go.
1. Be honest
Seriously, folks. You're going to work with children. You'll be a public servant. Do you really want to start that off with dishonesty?
2. Be yourself
It takes a certain kind of person to pack up their life and head to another country in order to teach children. You've decided to do this. You're a certain kind of person. So be yourself; let your personality shine through, because if you're sincere about this then you are what they're looking for.*
3. Be professional
It may be over Skype, and it may be from your little brother's bedroom because it's got the best wireless signal in the house. But take it, and yourself seriously. Clean up (or sit such that there is a blank wall behind you - sneaky trick) and dress up. In any job interview, you want to make a good first impression, and this is your chance to wow them with your dedication and professionalism. This plays into my next point:
4. Be prepared for technical eventualities
There's nothing that screams unprofessionalism like having to have your little brother answer the phone when they ring, and say, 'Don't worry, I'll fetch her,' while you're waving your phone around outside trying to get signal. True story. Not mine. No names mentioned here, but that was an example from a failed interview. And then you rush inside, panting, sweaty, and stammer/babble your way through the interview. Except that they can't hear you, because your onboard mic is picking up the whirring of your laptop's fan and so you sound like a cross between Darth Vader and E.T.
To hell with that. Get yourself a headset, and Skype a friend who lives as far away as possible, and ask them to tell you if you're coming through clearly. Save these settings.
NB - if you update your Skype, you may have to re-configure these settings. So, double-check them a couple of hours before your interview, and then don't touch anything. And you should be all set.
If you live in a third world wasteland like me, you may not have amazing first world internet. Maybe high speed internet is one of the main things that is drawing you to Korea (something else I wouldn't necessarily mention in an interview). One of the main reasons for laggy internet is that, even if you're uncapped, there are too many users on your line or you've pulled too much data and your ISP is throttling you. Make sure people are aware that you need them not to destroy the internet for a couple of days leading up to your interview.
5. Take the interview seriously
They are interviewing you for the job of a teacher in a public school. So it might not be a good idea to talk about how you're using this teaching gig as a springboard to travel through Asia. This is the education of their children, their future workforce, their future leaders, that you are treating as a free ticket. Screw you - go backpack through Thailand or something. This is a job interview, so talk about the job, and what you bring to it, and what you hope to get out of it. How can you make their organisation more efficient / effective / exciting? This is common sense, it's what you would do in any serious job interview, even if it was for a job sorting paperclips in a law firm in your home town. It's not about the free ticket to Korea or the free rent or the fantastic pay. Those are PERKS. They are REWARDS for being a GOOD TEACHER. So tell them what makes you a GOOD TEACHER.
6. Be relaxed and confident
EPIK have warned that it is unacceptable to have notes that you refer to in the interview. They're asking some deep questions, that you should definitely have considered beforehand, but if you're stammering, babbling or reading from notes, it sure doesn't sound like you mean a word that you're saying. They want to get to know you. Leave the rehearsed lines and cheesy waffle out of it; if you're honest, professional and taking this seriously, then you should have a good answer and you should mean it. Pause after a question to collect your thoughts. Take a breath.
You should also know exactly what you said in your application (without having to refer to it) because that's all they know about you so far, so they're probably going to ask you about it. This includes the lesson plan and essay.
7. Be clear
You're applying for a job as an ESL teacher, so your ability to speak clearly and concisely is also being tested. Don't rattle off in crazy terminology about your pedagogical beliefs about homogenous cultures and the duality of mind and body in a globalised social reality. You might sound smart but you're also showing that you don't know how to communicate effectively. Your accent should also not impair understanding by a second language learner; likewise, try to minimalise regional or dialectical slang in your speech. Cos, ja, bru, if you are lekker brief and keep it toight like a toiger, they'll smaak you stukkend, china. But if you're wack and late for days, they might not dig you. Aweh.
8. Be sparkly
Smile. Crack a joke (if you think the interviewer will appreciate it). Throw in a Korean phrase you've learned. Mention kimchi or your favourite K-Pop band. Dazzle them with your passion, interest in their culture and schweet personality.
If you keep these in mind, then I don't see how you can go wrong.
Good luck. :D
*Unless you're a drug-addled serial killer with paedophilic tendencies. Then it's probably best not to be yourself. And probably best to think of an alternate career path. Just saying.