For the facebook question, it's the same as the website tag of the other changeset, the contact:facebook tag is a duplicate of the facebook tag, they aren't meant to be both specified in the same object, and the tag value is the full URL or pagename, not a group name (see https://wiki.openstreetmap.org/wiki/Key:facebook)

putting the group in source:service_times makes the most sense to me, but there's not a standard way in OSM to define two different facebook URLs for the same object