If you install Linux first and then Windows on the same drive, it will fuck up your bootloader.
You can easily make Grub boot Windows, so just overwrite whatever fuckup Windows made, or install Windows first.
It won’t happen with a simple update, though, that’s for sure. Maybe if you’re upgrading Windows to a new major release.
No chance they will block out the entire EU market. They will probably just do the same as everyone else and make a specific EU policy.
Actually I think Meta Threads is still not available in EU for the same reasons.