Having used the web version of Office at my job, I know I would not pay for it. It is compatible-ish, but severely lacking in features, enough so that I don’t trust it to render properly or maintain the formatting entered using the desktop app. If that is good enough then there are lots of alternatives.

There are thousands of programs for Linux… but you should be warned that relatively few programs run natively on both Windows and Linux. In some cases there are ways to run “Windows programs” on Linux, but in general such successes are special cases. If you absolutely must have Windows you can run it in a virtual machine… but you will most likely be happiest with Linux if you aren’t chasing after such things.

I use Windows for work because our IT department only supports that… but I use cygwin and wsl to get a smidgen of my familiar Linux tools that I use on my personal computers.

Way too late for that. Every language I know makes some kind of auto conversion for numeric comparisons… and sometimes for strings as well.