Direct P2P, connections, Player re-join game

Hello there.

About P2P, I found that it is possible with NGO.
If the direct connection is lost or poor, is there any provisional process to send info through the Unity relay servers? if so, is it an automatic process or the developer must configure it?

Is it possible to connect to an external, owned server?
is it possible to send data directly from that server to another one, for example, the server Unity uses for matchmaking?
I found that Multiplay allows the dev to use external matchmaking. Is that correct? Is the same possible for Lobby?
Can a player re-join to his game if the connection drops down? how?
Is it possible to join to a game in progress? how?
I tried to find info about max players, and the only info I found was about lobby max players, and the value was defined by the dev. I'd like to know the max value for players for lobby and game session

 

About the lobby size, the max number you can set it to is 100 players