

The multiple power supplies are for redundancy. It will work with one plugged in but you are “supposed” to plug in both.
It’s fundamentally not that different from a consumer desktop. Plug in a monitor and a keyboard and a USB with your preferred flavor of headless Linux installer on it. Configure ssh as the first thing you do because you won’t want to plug the monitor and keyboard into it every time you need to tweak something.
You can probably find VGA to HDMI adapters if you can’t find a monitor with VGA support.
EDH was a community-developed format before wizards adopted and renamed it.
It’s a fun, casual format. There is a lot about modern MTG releases that suck but blaming a casual, community-driven format is a wack take.