Questions about dedicated server

Hi. Hope you can help me out. We have been creating a multiplayer game and only used it by having one player to be listening server. Now that we can go forward with out project we need to take step and create a dedicated server that will control networking. I have a few questions about the dedicated server:

The server should be keeping one level open and listen that so the players can join that level. From there players can create their own server or join another server. So can i test the dedicated server in editor the way that it keeps listening to that specific level? If i start the dedicated server the clients will spawn but everything happens in that first level and i don’t know how can i get dedicated server to listen the other levels.

Do i need more than one computer / server running if i want to do this: Dedicated server will listen the one level and when players joins into the server they can select a “mini-game”. When player have selected the minigame they will be launched to another level and that is too supported by dedicated server. So can one dedicated server listen multiple levels or how this thing works?

I only have done this with one player being the listening server so i’m little out of loop in this case. Thanks.