Easy to set-up and use but there's no English. I will say if you're experiencing issues check that your ARC name matches the name on your bank account. My bank account was listed first - middle - last unlike the ARC so I had to stop in the bank and ask them to change the name on my account to match the ARC EXACTLY (last - first - middle, all caps). From there you're eligible, and no, you don't need KakaoBank. Any Korean bank account is fine (I use Hana). You'll just need to link it to your Kakao account via the app and it works much like a bank transfer without all the little steps in-between.NaverPay is also great but I find a lot of Korean friends don't use it. KakaoPay has been great for me much like Venmo in the states (if you're American) to split bills and send friends money, etc. NaverPay is great if you actually shop on Naver. Otherwise it's really not useful in my experience, but everyone is different.If you don't know any Korean and don't feel like you can muscle your way through with a translator, get a friend of coworker to help you.
I installed the app and the lady was going to set it up for me, but it didn't end up working, even though she had all the info in front of her.She couldn't understand why it wasn't either. After about 40 mins, she said to come back the next day, as there might be a 24 hour wait or something. I went back the next 2 days and still nothing, so just gave up on the app haha.
The KakaoPay app? I just set it up through KakaoTalk app from the menu. In my case there was a popup after entering all the information that my ID didn't match so make sure your name in your bankbook 통장 is exactly the same as your ARC. Same goes for NaverPay - you need your Naver account name to match exactly to your ARC as well. I don't use the KakaoPay app.. just KakaoTalk so I can't tell you if it's any different.