Where to report problems with Shortbread schema itself? (Or suggestions what to add or change.) To the shortbread-docs repository?

Yes, changes to the shortbread schema should be reported in shortbread-docs.

Put the new version of osm-meta-emitter somewhere on the dev server. Have it configured

Nothing on the website can depend on the dev server. That’s why it’s a dev server. It doesn’t have the redundancy, access controls, everything in chef, and all the other stuff needed for primary and secondary services. The dev server also can’t always connect to the DB over a psql connection since they might be in different datacenters.

I don’t see any reasons why it couldn’t be on the frontend machines. If it’s a standalone service ruby would be easier to deploy, or it could be part of the existing website repo.