In the list of Actions that you can have a rule perform, I don't see any way to cause an item to be Moved to Archive. Is there really no way to do this?

It would seem an obvious choice for anyone that does not have AutoArchiving turned on. You could (perhaps) write a startup rule that would look for items in an ARCHIVE THIS NOW folder and shovel them out (other rules or manual action could put the items in the ARCHIVE THIS NOW folder). Or you could have a rule that would look in the Cabinet and archive anything older than X days.

Also, I see no way that AutoArchiving can be turned ON for specific folders but OFF otherwise. And I can't have AutoArchive retain items for longer than 999 days.

I'm surprised that after many generations of GWise versions such features are still absent. Am I missing something?