If you're not too particular about the quality and style of the submissions you receive, this might work out well for you.

Your style sheet is a good idea, but it will probably cut way down on the number of submissions you receive (which will probably be a good thing).

I wish you good luck, but I think you might be better off to ask for story ideas to write yourself, if burnout is your problem. If the problem is a lack of time in which to work on the story, then you've got a legitimate excuse for farming out the work (editing is MUCH faster than writing).

I just have to remember past attempts at shared world stories (Camelot, Merovingen Nights, Thieves' World) and how uneven the results from those was.