I've been considering getting one but I've read too many horror stories about them breaking

$0.14 per user per month is... Higher than I expected.

Demon beast

It doesn't look like this functionality exiatings currently either on the Lemmy end or the client apps (Jeroba). I'd probably wait for things to settle a bit and raise it as a feature suggestion for Lemmy

Yes it's FOSS: https://github.com/dessalines/jerboa/blob/main/LICENSE

Unsure on the rest