What is daily life like in Seoul?

Hi everyone, I'm researching daily life for international students in Seoul because my daughter plans to study at Gyeonghee University. I'd like to know where students usually buy personal items, and if the options are as common as in Vietnam? For example, are there enough supplies at convenience stores (Peace Stores) and department stores (Dios) and what is the quality like? Is using public transportation and buying transportation cards (Gyotongcard) or T-money complicated for newcomers? I'd appreciate any practical experiences shared by those who have lived or are currently living in Seoul.