You're never forced to update. I'm don't even think Arch natively supports automatic updates. You can also tell pacman to skip a package from being updated if you're aware of a problematic update but you want to update the rest of your system.

And yes, Arch takes in the upstream vanilla packages, though there are testing phases before updates reach stable repos. I'm not sure any of this is a bad thing. It also means you don't have to wait 6-12 months for the newest version.