I've never really thought about these characters in terms of symbolism, as there is so much symbolism in the story, which is separate from the characters themselves. Thus, if I have to look at Heidegger in terms of what he represents..... I'd have to say wisdom. In the end, he's the only one who doesn't take the elixir.
In terms of Hawthorne's characters, I believe he's trying to disprove that old saying, "If I had it to do over, I'd do it differently." Another saying that comes to mind is, "I wish I knew then, what I know now."
Please list your questions separately. Also, try to post your questions in the correct category.