1) Usually slightly unsatisfied. My first few were panicked efforts close to the deadline, and they weren't very good. Later on, I've written stuff that I'm more satisfied with, but have worried about whether it really meets the request.
2) Handling drop-outs by having pinch-hitters seems good. I've no idea about complainers, since I've never been one.
3) It's a good idea. I'm in theory up for doing that sort of thing, though most deadlines have come when I've been too busy for a fast turn-around.
4) Snarry Detention ficathon. It was the first when I did a decent job.