1. 아니, 아무것도 아냐. 2. 감기약 알아? "FOR" can be translated as "~을 위해, 위해서, 위한" but sometimes, like in this case, it's better to omit it. If you insist on saying the phrase with "FOR" anyway, then it'll be something like 감기를 위한 약 알아? but again, 감기약 is an idiomatic noun for a medicine for cold, no such redundancy is needed. Speaking of your example, I guess the best way to put it in Korean is like 나는 이것을 공부하려고/~하기 위해 샀어. ~하려고 also means "FOR" but modifies verbs and in that sense, is more like "TO". I hope this helps.