With Update 1 do I need to upgrade all the standalone installs also?
And is it recommended to uninstall the previous version and install the update or can I just install over it?
It’s recommended to also update the standalone too, yes. Both standalone and V-Ray for Maya have code changes compared to the previous versions and it’s good to keep them in sync to avoid any potential issues from mismatching versions.
If you run the installer - it will automatically uninstall the previous version.