I think your first translation is good and correct. It matches the words with English, and it sounds pretty natural. 吃香 is also a very good use of slang. It's just one way of speaking of the suggested answer - 他很受学生(的）欢迎 .
For the second sentence, I would say: 很多学生通过了考试，我也过了
I think it's good that to have word-word translation, but the purpose I learn ...
Well, sometimes you won't translate 'among', see your first sentence. Other times, 'among' will translate simply as 中, or a combination of 在 ... 中, like your second sentence. 在 ... 间 is also common, but there are other ways. Of course, exactly if and how 'among' is expressed will depend on the context.
He's very popular among the students.