Since UE4 does not have a proper CMS we don’t have source control for art assets and instead assign each map to an owner who oversees the development of “that” map.
Internet based project.
Environments are built standalone and what ever package is required is added to that project.
As above yes
When the project is ready to be consolidated the “level” is migrated using the levels and it only migrates the assets used in the project
Using sublevels a level can be added to the mix and updated. When the persistent map is loaded the sublevel that was edited is included with out worrying that on -going changes will change as well.
Once consolidated the map owner can then decided what art assets have a common use and add it to the common asset pool. Since it is used in a given environment it ensures that what is added to the consolidated build is in use and not bloat the build with unused art.
Source control of art is done visually as the owner can see if something has gone wrong.