@Noggin Sorry I’ve not got much time on this one but re:
Quite possibly. You still need to scrub the pool, as you tried but I suspect you have either bad PSU or bad ram. Investigate those before you try anything else at the OS level as with bad hardware all OS/fs stuff is essentially doomed.
Not necessarily. I would say if you don’t need AD then definitely go with the openSUSE as it’s btrfs core and kernel are years newer and given btrfs has seen some significant imporovements in this time I would definitely go for the openSUSE variant via the DIY installer build method:
But in your case I strongly suspect hardware first. And the pool damage is due to that. You may not be able to repair the data pool but you may very well be able to retrieve the data, even if you have to mount read only.
Let us know what you find. And I’m assuming you are aware of utilities such as memtest86+ or whatever it’s called these days.
Hope that helps.