Yes, CoMaps lets users submit basic data that updates OSM for addresses and POIs. It's a harder problem than you may initially think too, quite often the delivery format of OSM data differs in schema from the DB format. In the case of OrganicMaps and CoMaps, they both generate offline-optimized map formats for distribution.

They can’t do so automatically. Osm Editors must approve. Apparantly OSM fears legislation when people copy info from google maps. They like to see evidence, like street sign photos. In my limited experience anyway.

I assume they all do, it's nigh impossible to maintain your own data fork and keep reconciling your users' edits and the updates from OSM.

Of course they do.