My vote is for number 2a. If you think it's an awesome idea and that it might be publishable, you should go for it.

And I don't believe that someone as devoted to her writing as you are could "wreck it," and I also don't believe that there is ever such a thing as being ready to write a novel - If one waits for an ideal state of readiness, one will probably never feel ready enough to settle in and write.

So jump right in there. It'll be fun. ;)