Steps 3 and 4 are all handled by Unreal networking and the normal client/server architecture of the engine. You don’t have to be offline to have a lobby. The server can have a lobby map with game logic for character / weapon selection. When the game determines that all players are ready it can seamless travel to you map and play the game. It can even travel back to a lobby between maps or chose to disconnect everyone back to the main menus and start again.
I’ve begun to answer questions about similar setups in the thread about Paragon Servers