Performance wise, does anyone know if Linux is actually better than Windows?

It really depends on the title.

what Edition would be the best for me?

Better start with the official one - Cinnamon Edition.

Where can I download Steam games in Linux?

In Steam. Just like you do it in Windows.

Is it a good idea to Dual Boot between Windows and Linux?

Yes. Just try to use Windows only when necessary. You can always drop Windows when you feel like you don’t need it anymore.

Screen tearing on Linux? You have TearFree disabled?

For free? 4090. I would sell it and buy 7900 XTX.

If you’re new to Linux, i recommend some user-friendly distro instead going for best gaming bleeding edge Arch-something. Try Linux Mint and get used to Linux. You can always switch to something else later.