I have lived Korea for the better part of 5 years. Download Naver which is basically Google for South Korea. It has English capabilities which will be helpful for your trip too. IMO, bussing or training will be easy. I do believe if you train, you will have to transfer which is a pain and would personally choose to bus. Busses should be running normally again as tourists are entering korea again.
Here is a quick google search for the 6015.
https://www.myeongdong.org/2013/10/b...l#.Y4J0bi-B1-U