How does one volunteer to be Region Manager?
how much time would this take up?
That is totally up to you.
I more or less regularly take a look at my local region, as I know that my city often gets created in the wrong region, and then when I have free time I drop by this forum and see what I can help with. I leave more difficult and iffy stuff to those who are more experienced, and mostly handle simple merging of duplicate zones.
You are not obligated to do anything, you are just given the tools to help, and you can jump in whenever suits you best.
I'm feeling a bit guilty after putting in 3 requests in one day and not wanting to overload whoever is supposed to be covering Hawaii.
Not that I have a ton of time to devote to it, but I'm currently one of the more active book releasers in my city, so I suspect I'm one of the most likely people to find zones that need tweaking.
Of course, that's only for Honolulu...for other parts of Hawaii I don't know much more than someone from out of state. :s