Yuletide for bystanders

I have had multiple people express some confusion over this "Yuletide" thing I'm doing, and while there are FAQs at the Yuletide site, they're more focused on participants. So here's a quick info dump for bystanders.

(Those who know more about Yuletide than me, please let me know if I've said something inaccurate or misleading.)
( More info )

tl,dr: Yuletide is for odd fanfic; please don't talk about what people may be writing until New Year's Day.