You can't.
It's an event that seems to happen randomly, usually in the summertime, but not every year, but it would be announced in the news.
Welcome. What some people do is save up books in their vault or a gallery so that when the time comes, they'll be able to donate. :)
No problem, and it is sort of sad. But I believe staff said they were thinking about doing a different kind of item drive since books are expensive/rare enough without us essentially deleting them in the drive. Some other way to make the prizes more available perhaps.