It is pretty polished to be daily driven. However you might miss some more features in settings and such if you're coming from something like KDE.

They have released a newer version with COSMIC as the default DE

Yes, I have an extra copy of the data in an external hard drive.

And what about the data? What is the best way to manage them?

I used to have issues when I tried to run fedora and ubuntu, hence the title.

Yes, I have used the arm version.

It is like Virtualbox only, but exclusively for apple silicon https://mac.getutm.app/

Ya perfectly, without any issues. Because the distro uses directly MBP's wifi ethernet style.