I don't have a full answer, but my experience with the void.
It can hold at least 4 villagers, possibly more. They do not get cleared with time, the villagers have to all get moved in. I know this because the void conflicts with amiibos. If you have an amiibo villager, you cannot invite them if they are already queued to move into your town.
In my case I wanted Erik, it said "he was moving" and couldn't come to my island. I then bit the bullet and let a bunch of villagers leave and allowed random voided villagers to move in until Erik finally showed up.
The villagers will mention the town they came from when you first talk to them, then never bring it up again. They don't seem to inherent catch-phrases or clothes...or at least the ones I received were never given any.