I appreciate that it seems easy, but I have not figured out how to use the Metadata panel to automatically write comp and project names to files as they are output.
I can see how it might be useful to add such information manually to files once they have been rendered, but that's about as as far as I got. Is there a way to get AE to write the name of the composition and the project into the file metadata automatically?
You could write a script if you need custom data. In the output module there are check boxes for Include Project LInk and Include Source XMP Metadata. This may be sufficient. The include project link means that when you open the rendered files in another app like Premiere Pro and you edit original, PPro will open up AE and look for the original project that created the movie.
There's a bit of info about how this all works in the help files and on the community search (see above).