Yes the kit does not rewrite how networking in unreal works. When you host you become a listen server. You can also run a dedicated server just like any other unreal project.
Nit sure what you are asking as if two players were on different maps they would be on different servers as unreal loads one map per server. Unreal supports a huge map size and with terrain paging yoi can create some really large and detailed worlds. Also i believe in 4.14 they added world origin shifting for multiplayer which allows to create even larger maps with that technique.
There is no persistance or saving or database integration. As it is a blueprint only project for the marketplace it is not bundled with advanced c++ logic or plugins needed to do that.
The project is a clean base to help prototype your idea and build a game upon. But it is a starterkit and helps you get into building as a lot of the initial setup is done for you.
I hope that helps clarify things.