You seem to have studied Korean language from a structural point of view, which I think is a good way to learn a language, applying a general rule to many instances. Here's my answer. 'na' means "me" or "I" you should add a kind of suffix to "na" in Korean for the pronoun to have a grammatical case in a sentence. So when you add "neun" , then you have "na-neun" which can function as a subjective in a sentence. Adding "reul" makes "na-reul" which means "me", acting as an objective , so it should be placed before a verb in Korea. (This is the biggest difference between English and Korean grammar: English has S+O+V sentence structure, while Korean has S+O+V order.) In "nabogo pyeongbeomhadanda yae", "bogo" is not an infintive tense- to see . It's a special kind of suffix for a subject in a reported sentence . In this sentence, with the suffix "-danda" which is used when reporting a remark you heard from others, the subject ending with "bogo" is the subject in a reported clause. After all, this sentence translates to " They(She, or He) say that I am normal(plain)" One more thing, usually only girls use "yae" as a vocative to express some friendly relationship. And your phrase "naro pyeongbeomhaneun bwa yae" does not make sense to me. "ro" is a suffix for an ojective complement in Korean language. So i'd like to correct your phrase, as " nareul pyeongbeomhan aero bwa " Here, ae means (younger) person. (Translated to " They see me as a normal girl" Hope my answer is some help for you.

I think, "가을 학기 동안에 한국에 계실 건가요?" would be good.

In this case, "첫인상하고는 다른" which means (somebody) being different from what was judged by first impression" modifies "사람(person)". So this sentence translates into " We came to find that somebody is totally different from what was judged by first impression, and then become good friends.

Hello? You can say " 집세 내러 가야 해요" ( Jip-se naereo ga-ya hae-yo) for " I need to go pay my rent." and for "Be patient", you can say "침착해"(Chimchakae!) or "조급해하지 마" (Jogeupe haji ma)