oops, I posted elsewhere on this one before I found this thread.
I agree with Rhym on the career question - it's what they all ask for, UNC is just more explicit and gives you the room to address it.
And I also struggled with the challenges question; still am to be honest.
I would like to organize more according to a few goals - maybe a professional one and something more personal. And then spend most of my time talking about the challenge and how it affected me. It seems a better way to organize the essay, especially if you don't have some general, all-encompassing challenge to write about. YOu know, your prostitution issues or something along those lines.
how did you guys do with it, since I see that you are way ahead of me on this one?