Definitely go for it, that's a great thing to do!
Going over your classes, here's what I would advise.
"Questions that should have been closed, IMO."
If feasible, edit to improve; be ready to take ownership of the question.
Otherwise, vote to close; the question will then end up in the
review queue and may get closed (or rescued) by others.
Go for it. I do go over top voted unanswered questions every few months
(as I did last week). :)
If you can answer a question there is no problem with bumping it up, do answer!
If you can edit to significantly improve a question that is also completely fine. Just don't do too many small edits in a short period of time. If it is a significant improvement ...
The general rule is: don't edit questions in a way that would invalidate answers that were correct at the time.
If all existing answers are incorrect or incomplete, we get into a gray area. On the one hand, we don't want to flood the site with duplicate questions just because they didn't get a good answer the first time round. On the other hand, if your ...
A questions counts as unanswered until is has (at least one) answer(s) with positive score or an accepted answer.
Source on meta.SE
We mix semantics of "answered" here; do we mean the OP got an answer, or there is an answer-type post? The naming of the "Unanswered" tab assumes the former meaning which I think is fair.