My homeserver runs Debian with Freedombox, and I’m using their GnuDIP ddns service, but it’s for free subdomains, not your own.
I used to have a script to update my own domain in Gandi console. I only stopped because I didn’t really need a domain for my home.
Raid5 of three disks and keep the fourth as cold spare. That’s 16TB instead of 24, but you’re barely using your current 8, so a spare makes more sense.