Lobby or not lobby ? That is the question..

Hello ,
i just read the doc about the lobbies ( https://doc.photonengine.com/en-us/pun/current/lobby-and-matchmaking/matchmaking-and-lobby#lobbies ) , and i dont understand if i would create a lobby manuelly or not and for which situation.

First question : How many rooms can have a lobby ?

Second Question : If a Client01 "CreateRoom" >>> that create a lobby too, and a Client02 "CreateRoom" that will create a lobby too or rejoin the first lobby ?

Third Question : If i want create a game of Smash Bros by exemple, then battle of 4players per room. With a typical menu for join a game battle, same style than plenty multiplayer videogames : list of games battle(rooms) with number of players in and number of players capacity room, and a possibility to Quick Match for join a random room not full and a Rejoin Game for join a room specificly and possibility to filter the Games List with options (map, game mode etc).
Then in this case : what i have to do with my lobby or lobbies interrogation ?

Thank you.