My first NAS was a HP Proliant N54L that I ran Ubuntu 12.04 on. Of course, I rebuilt it several times and it ended up with Ubuntu 20.04 on it (hitting every major LTS release along the way). Ran that until just a year ago when I replaced it with a Synology RS-422+.

I went with the Synology because for the price I couldn’t really build something with hot swap drives, 1RU, and shallow depth. Now only use my Synology as a true NAS. I don’t run containers or anything else on it. Strictly an iSCSI/NFS/SMB solution to support the rest of my network.

At any given time? Up to 234 kW but that's only because I don't have anything with more wheaties than a 5.3 L LC9. Less than 500 W for the lab though.

Get as much core infrastructure stuff as you can with SFP(+ or 28). Uses DACs where the lengths dictate (fairly reasonably priced) and transceivers/glass where you need further runs or confined space pulls to other rooms. Where you absolutely have to go with copper transceivers. For example, the only 10G I run at home over twisted pair is from my synology to my distribution switch. I only have one workstation that runs multigig which is my editing/gaming PC. Everything else is gig so no worries.

Nope. I have a Zima Board that I am actually doing some experimenting with right now and when I took it out of the box...I PXE booted Clonezilla and then installed Alpine...then Debian and I'm constantly PXE booting other things (WinPE, MS-DOS, RHEL 9, etc).