Watch for battery life when buying older Surface devices. Replacing batteries in the older Surface Pros is notoriously difficult, because apparently the whole assembly is glued together. Loss of battery life is what forced an early retirement of my 5th-gen (2015) Surface Pro, even though not was otherwise completely serviceable. Newer versions are apparently more repairable, but you’ll have to investigate where that cut-off line of repairability is.

I mean, I think it started as a BSD fork with a Linux kernel jammed in so… you’re not far off.

(Brace yourself for Much 'Merica) Several gas utilities I’ve had in the USA measure natural gas CCF, which is 100 cubic feet (at some standard temperature/pressure), which happens to be almost exactly the same as a Therm, or 100,000 BTU.