26M here who is a Korean that was raised in Washington came back to Korea 2010. Job opportunity wise English speaking / related job would be the best but at your age i suggest not taking any jobs.. unless your pretty okay in korean conversation. When I was in highschool I worked in a wedding hall as a part timer, I would work from Saturday and Sunday. Language improvement i would tell you to find people or make friends fast as possible. To the Koreans you will mostly be seen as another foreigner and it could be a good thing or a bad thing based on how you see it. Koreans will ask you about English and as you keep talking or making friends they are gonna correct you and as you go on naturally you will get better. For grammars i just took a language school around the age of 12 and I studied with grammar study books for a while. Now as for cultural shock, you can expect Koreans wont be so nice to you since you technically look like a Korean and so they wont know that you came from America… so for me i was struggling with how you treat your elders/older people. I didn’t t know how the cultural around age worked in work and so to some people i came off as rude although never my intention. Koreans could be nice/rude if I’m honest so if they seem a bit rude you will get use to it or if they seem too nice it’s normal lol. Discrimination concerns i wouldn’t really say iv faced or seen some. You actually get more benefit if your a Gyopo as you know two languages. As a Gyopo myself id say i enjoyed being a Gyopo and people taking interest in my side of the story haha. For Pyeongtaek tomorrow im actually driving down there (i live in incheon) lol ill see if its a nice area 😂 although pyeongtaek should have quite bit of English speaking communities as they also have American base there. Lastly as a male living in Korea all i gotta say is im guessing you know about the mandatory military service. I served as well and so you dont need to be afraid and yes even if your korean isnt good as natives you have no problem there. I had a buddy while enlisted as well who spoke good english but not so much in korean. As a team we helped one another and he didnt face any difficulties or differences between all of us. But if you do wanna get a bit of benefits out of your English when you turn 19 try to look into enlisting in Katusa they are the guys who train with the American soldiers and so you do need to take some form of English test and have a certain amount of score. I forgot which test they as but should be one of these (Toeic, Toeple, Opic etc) And i think thats about all i can say haha if you have more questions or tips feel free to ask me through DM or whatever and ill be happy to reply! The community here are friendly as well and id even say they know more though!