To be safe, you should always have a Roon database backup, which contains all the things you listed:
If you don’t have one yet, create it now just in case.
But to update on the same machine, normally it should suffice to just quit Roon completely (including the RoonServer process), download the current Roon installer, and install it.
Like I said you shouldn’t have to restore the backup if you move to 2.0 on the same computer where 1.8 was installed. It should load the old database and perform a conversion automatically.
But in the unlikely case that anything goes wrong, yes, you would be able to restore the 1.8 backup with 2.0. (And always have backups in the future, things can go wrong without warning at any time)
I would clean up the library in the settings beforehand. It’s always good to have everything tidy before a move and to get rid of old junk. Just like in real life…
I upgraded to Roon server 2.0 on my Win11 mini PC. All good. The whole process was simple and all my stuff migrated from 1.8 to 2.0 fully and effortlessly, contrary to my fear.