1) Koreans tend to place high value on foreigners, more so on white people. ALot of them are trying to learn English, that is why they will value a white person highly. You should try to tutor if you get a chance, you seriously can make much $.
2) That phrase directly translates to "You're cute"
3) Can't believe you;re asking this question. B/c stanford is a well established university, and anyone will be impressed by it. Korean women will likely recognize the name.
Sarging will be difficult, I was there last summer. If you can't speak Korean, you're going to have alot of trouble. And even if you could speak Korean, sarging strangers, you will have zero number closes. Talking to strangers in Korean society is considered suspicous behavior. If you try to talk to random korean women in the subway or on the street, they will likely run away from you, not j/k. They are not open to talking to strangers. Go to Itaewon, its a part of Seoul that's full of english speaking foreigners.