I would prefer the town hall format to a debate.
I think the questions should be chosen from submissions made by the citizens and put out on the web and in newspapers several weeks ahead of the meeting for the public to vote on. The most popular question(s) from the various categories would then be put to each candidate. The question would not necessarily be posed to both candidates since the questioning has been determined by whatever the overall voting population stated that needed to know about or from the individual candidate.
It's our country let us decide what we still need to know and want to ask!!