Moon 280D best computer setup

Yes! Jriver for the win. Enable SoX and load file into memory in the settings for best sound quality.

With regards to the fan noise from the computer, you can set cooling to passive instead of active under power options. If that doesn't work, you can swap the fans for silent ones. This is very easy to do.

If you're only using it to play music, any laptop with a SATA 3 SSD or nVme storage would be ideal. I would avoid hard drives as they are much slower and noisy.

I do not have that particular unit (the 280D), but in the last 10 years I have used the original MiND and half a dozen other streamers and also run audio files straight from computers with JRiver to USB DACs. IMO, in a really good system, the sound has been better through Ethernet than through USB. And, as you say, the noisy computer is removed from the room.

You already realize, the setup is a little more complex. Instead of just a computer and the DAC, one typically needs a server program on a computer or NAS, the DAC, and a tablet or phone to control everything. That’s for a DLNA/UPnP system, anyway, which is what the original MiND supported (and JRiver provides through Media Network).

My own setup has a NAS running MinimServer. An Android tablet runs BubbleUPnP, and it controls an Auralic Aries G1 streamer (similar to the MiND).

You could run JRiver’s Media Network on your laptop, put it in another room where you won’t hear it, and as you say, use a tablet to control everything. It works best to use Ethernet for the server (laptop) and streamer (280D) if possible. WiFi can work, but it’s more prone to dropouts.
I hope that helps.