How to make a lobby or waiting room?

Hi,

1) In all uNet examples that I've seen so far, people can drop in and out mid game but in my game people should all be in a lobby or a waiting room and when there is enough people there, it should start the game for all players at once.

2) Also I need a "Quick Match" setting in which it should search for any running game that has less than like 4 players and put the player there in mid game.

How can I achieve these two? An example would help.

Thanks.