I would try searching for the model number in google you will probably find some r/c fourms as they use server psus for battery charging quite often.
You will have to jumper one or more of the small pins to turn it on to get the 12v out.
You can have drives of different sizes in zpools. The stipulations are that you have to add the same type of zfs and same size. So if you create a 7 disk raidz1 you can expand the pool by another 7 disk raidz1, not an 8 disk raidz1. IIRC you can not shrink a zpool.
I dont sleep the drives. I have gone back and forth on that but most of my drives are from older enterprise storage so the power on hours were high when I got them so didnt want to take a chance of the spin cycles taking them out.
I have only added: docker, snapraid, megerfs, and msmtp. So my installs are limited on the base os. Proxmox has built in data collector that i send to a grafana LXC, I have also tweaked the unraid Plex grafana dashboard to work with my plex lxc.
The one thing I dont know that you have with your...
Any reason you dont want to use proxmox as the base? It does zfs (w/e disks you want) boot out of the box with no fuss. Have your rootfs and your 10 disk pools for vms and LXC, for docker install on the base install or put it in a lxc or vm. I am currently running all of of the above. I have...
If you asking if you can access the web gui from the proxmox box itself then you are correct you need a second computer as there is no gui install with proxmox. It is debain so in theory you could install a gui and manage it from itself but not a great practice.
The fans are not controlled by the mb they plug into the expander board so thermals dont mean much and they just spin at pretty high rpm. You could move the connection to the mb and it will quite it down a bit.
Here is another, looks like 4+ its 139 maybe lower with offer option. Seems like 10TB sas you can get to $14/TB or lower.
HGST Ultrastar He10 0F27438 HUH721010AL4204 10TB 3.5 7.2K RPM SAS 12Gb/s 4Kn HDD | eBay