Hello Gokhan,
Yes, you are right. To get the list of users available in the room you need to call getLiveRoomInfo.
Room properties can be used for match-making. For example, if game has three difficulty levels say easy, medium and hard. You can create rooms with property having one of the above values. If a user is eligible to play easy difficulty level then you can join him in a room with property "easy". Similarly, the properties can be used for geo-based rooms to join a user based on thier location matching with room properties.
To know more about properties please visit this doc.
Thanks.