Unity Multiplayer What kind of server i must dev for my project

Hello,
I want to make a general server where players need to connect to play my game.
I have done a login system using WWW to send data to a php page that return the login result and if it is ok it return also the IP of the server.
The server must host some game rooms managed by the room master (The player that create the room).
I wont make p2p connections between roommaster and other players, i want to make all server based.

Is master server good for this?
What do you think about that?
How much rooms do you think it can handle? The game is a simple 2D games that use some physics so i need just sync between all players and about another object that collide with players.

Sorry for my bad english and sorry if i'm not too much clear

Thanks in advance,
Lup.

 

#bump
(i hope this is allowed...)