These days a source tag on the changeset itself rather than the OSM objects edited is sufficient, see source=* for some background. For instance, on your colleague's recent edit, changeset/179643467, source=survey;dashcam on the changeset is suitable, that information does not need to go on the way. For this edit, I do not think any gps data is your source, it's really just general knowledge about speed limit units in the US.

Is Glen Echo really currently a theme park? I don't think there are any rides except for the carousel, otherwise it's more of a cultural center. Maybe disused:amenity=theme_park?

Reverted in changeset/179653761. Feel free to re-add the camera, but be careful not to touch other ways if you don't mean to!

Hi, please be careful not to drag nodes and delete things unintentionally like this, your edits go live immediately. I am reverting this

Hi there, thanks for doing this check, it seems like these roads did need the mph in their speed limits. Can I ask what the source=gps is supposed to mean? It seems wholly unnecessary on the ways, and presumably not even true unless you are surveying each of these roads personally

This coffee shop is permanently closed, which is why it was marked as disused:amenity=cafe.