I doubt old versions would be supported (the requirements can be found
here). Adobe have made their versioning too difficult for me to follow. But the current apps generally only support the three most recent versions of MacOS. Something as old as CS5.5 might work on a newer MacOS, but it's hit and miss, Adobe won't be going back to fix it.
You can install the upgrade and
roll back to a time machine backup if it doesn't work.
Alternatively, abandon the old Adobe apps. I seem to be doing a one-man advertising campaign for the Affinity apps – Designer, Photo, and Publisher. Affinity Publisher is a very cost-effective and fully capable replacement for InDesign (I prefer it, it's lot less clunky). There's not even much of a learning curve.
Catalina, by the by, is about to be replaced by Big Sur.
No idea about the WatchOS thing, but generally MacOS, iOS, and WatchOS are synched, so support will drop off for older versions. Works fine here, but I have Catalina.