Hello! A few answers to your questions:
1. Yes, the "people" mentioned in the second line refer to "young" people.
2. The "--" is sometimes used in place of a colon (:). In the above paragraph, it seems to be used that way. ( It can also create a pause within a sentence, but it is mainly used that way in poetry.)
3. That is an interesting opinion! You can definitely make an argument to support your opinion.
4. In this case, "young one" is just an expression. "One" can sometimes stand in a sentence for "he," "she," or "a person."
For example, I could say, "When he gets mad, he yells." I could also say, "When one gets mad, one yells." They both mean the same thing. In the sentence above, "one" and "man" would both be correct.