Well, time to edit .bash_aliases…

Can’t speak to your exact machine but nowadays the license tends to be tied to the hardware.

If you are capable of manual partitioning then you should be able to reinstall Windows quickly if needed.

I would go with 16GB for the kinds of things you listed.

If you don’t need a 3.5in drive then I would go even smaller to a mini form factor. It will definitely save you money on electricity. I think it’s the main choice here.

I would go for refurb, business line SFF machines. Something like ThinkCentre or Optiplex. Specific form factor based on drive needs but the smaller you go the more power efficient. I have one on the bigger side (internal psu) that runs about 12W idle.

Just double check that it can handle hardware transcoding. Should fit right in your budget!