I didn’t say it was unobtainable. But it might look/behave quite different than the tools you are currently using.

As for Microsoft Exchange, I only use that for work, and my employer would not allow me to connect from my personal machine anyway. I am not saying that you that you have to give up your favorite tools… but I am saying that it you are putting up so many fences then you might as well stay with what you have.

No.

If you ever so carefully paint yourself into a corner then the corner is where you will be stuck. How badly do you want out of your corner?

There are FOSS and SAAS options that could work if you wanted them to… but whether they will depends on you.

Meat eaters trying to become vegetarian for ethical reasons often fail because the “un-meat” options out there don’t meet their standards. Success almost always requires some letting go and re-adjusting. If you are not open to that then don’t force yourself to put up with something you don’t really want.

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.