Recently I featured a Videojug video of reality show producer Marc Cronin explaining the business of reality shows. In the video below he addresses the questions of most interest to writers: what are the essential elements of a great reality show, to what extent are such shows written, and how do you create a "set piece"? He also talks about how the story department at his company (Mindless Entertainment) shapes the storytelling.
I think you'll find it interesting even if you don't want to get involved with such series: