Check compatibility for all your programs before you move. Most Linux programs work on Windows but not vice versa. If you’re not in a rush, try switching to programs that have a Linux equivalent before you move so that you’ll have less of a culture shock. If you need any killer apps that don’t have a Linux equivalent you’re going to have to make your peace with that ahead of time, otherwise you’re just going to end up switching back.

KDE is a good choice, and Kubuntu should serve you fine; if you end up going with Kubuntu, I would recommend sticking with it for at least half a year or so before considering switching to something else, as that will give you time to really understand what you like and don’t like about how Kubuntu and KDE work.

I imagine this would be backing up to Signal’s servers, not restricting local backups? Seems like a harmless way to raise money; I’d wait for a blog post for them to explain their reasoning.