Self hosting email sucks. Unless you just want the learning experience, pretty much major email service will mark your address as spam. I'd just get the lifetime account on mxroute (pretty sure it's still available).
I have tried using raspberry pi (3B) as media / file server. It's running, but for some reason, the HDD won't spin down even when no one's accessing the drive. The drive is extremely hot and loud. Gave up on that.
That said, everything else would work just fine. My pi is running pihole, octoprint, and CUPS. And it barely need any maintenance.