I would like to apply the Film Grain FX to the whole project. I know you can Copy and Paste FX between clips etc. but that isn't applicable for various reasons in this case. Can one apply a FX as a "Master FX for the whole project or a entire timeline?
Yes, drag the FX and drop it on the preview window AKA the video bus track. Now the whole project will be affected and everything will have to be rendered.
If you want to see your video bus track, hit Ctrl+shift+B. Applying an FX on this track is the same as dropping one on the preview window. Right click this track to apply motion blur, supersampling or use it as a master fader.