How best to set up a second PC with MSFS?

I run the store version of MSFS.

I am about to set up a second copy, via Steam (I bought a second copy way back when I was having issues with the store update process but never got to install it) on a separate PC.

This second PC is the one I used as my SimPC until I upgraded my PC last year, so it has a copy of the Store MSFS version hard drive on it.

The reason I want to do this is that firstly there is no real worthwhile resale value on my "old" PC, and anyway, selling a used PC involves opening several cans of worms, so I figured I'd just use it. I've bought a decent-ish 2k monitor for it, and I plan to use it with my Honeycomb Alpha and Bravo controllers, which I don't use on my main sim pc as I don't really have room for them, but I'm planning to initially set up the second PC in my workshop and if I get it working satisfactorily I might build a mobile trolley/workstation for it and move it to the man-cave. I figured I'll maybe use this setup to actually get a bit more familiar with some of the actual flying stuff that I currently mostly ignore, as the whole yoke and throttles thing might encourage that.

So I have a few questions, mostly due to the cloud based nature of the sim.

1) I'm assuming I shouldn't just run my exisiting store version on my "old" PC? I believe I'm allowed to do this legally as long as I'm only using one of the two sim PCs at any one time, but I really, really, really don't want to risk changing settings of any kind on the "old" PC that affect the main PC in any way whatsoever. A lot of the graphics settings are going to be different across the two PCs, for example, and I don't want to come back to my main PC after setting up the "old" one and find my main PC is now running at 2k and non HDR, for example.

2) assuming that the only way to really guarantee non-interference across the two systems is to not use the same copy (i.e. not start up the existing store version on the second PC using the same userid as on the primary PC), should I specifically remove (uninstall) the store version from the "old" PC? And if so, is there some weird process I need to do via the gaming/Xbox app to do this rather than a traditional "uninstall pgm"?

3) If I install the Steam version on my "old" PC, I assume it will be tied in to my steam ID and completely unconnected to my MS account and store version? So anything I do in that version will have no effect on my store version on my main PC?

In any other environment I wouldn't need to ask these questions, but I'm really unsure about all this "online gaming" stuff. Life was a lot simpler when I just knew that I installed something on my PC and that was it. If I wanted a second copy on a second PC there was just no question of any potential interaction. It's not as if I can even just think I'll leave the main sim PC switched off while I set up the other one - I'm sure if they're gonna interfere with each other they'll just do it later when I power the main PC up next time. Roll on the arrival of quantum hard drives or whatever so that we can all just download all the petabytes of stuff that we now have to access via the cloud!

Anyway, any info/advice gratefully received. I did check through the tips and tricks forum but didn't see anything there, but if anybody can point me to something I'm more than happy to wade through any documentation out there.

cheers,

Andy