I would like to go to Seoul as a volunteer in a hostel and would like to know if the visa free entry as a tourist is enough for that purpose (not getting paid, just accommodation). Also, how exactly does the visa free entry work? Do I need anything other than the two plane ticket printouts?
I have lived in South Korea for few years and the Visa Free Entry would actually work for this purpose as you are not engaging in any paid employment. What is your expected duration of stay in Seoul?
South Korea Immigration is helpful and polite. They don't typically ask for any documentation if there is no Red Flag :-)