What does <word/noun>+하셧던데 mean?

What does it mean when someone tells you, "多關注"?

Is this correct? I'm trying to say, "having black hair looks more natural" or something along that line. Is this correct? "머리는 검은색이 더 내추럴 해보여가지고" And does 시름 mean bad/horrible?

What does 읏엉 mean? Like in "왜 읏엉?" I know what 왜 means..

How do you say, "I was just being polite" in informal Korean? I was talking a bit formal to a younger Korean since i don't know her personally. She was surprised, asking my age. How do I say I was just being polite?

"거긴 후배 안혼내요 ㅠ?" Can anyone translate this?

Korean military service...When you get enlisted, do you really have to cut your hair? I'm just curious... Coz I heard there's a department where you don't have to cut your hair and they have cool uniforms.

What does 잘나왓당 mean?

Can anyone translate this please..? "밑에글이안써져요.. 저그냥네이트판에서봐가지구요" My Korean still sucks and I can only make out a few words from this ㅠㅠ