Hi oOScuByOo
2. Try room and player properties. These properties are synchronized automatically among clients connected to the room as soon as any player updates the property. For instance, level selected by a player or flag set if he accepts the given level can be represented by player property. The currently voted or played level is a room property.
Also you can keep entire game state in game properties. This is the simplest way to synchronize it (assuming that it doesn't change very frequently).
3. I think you can have global object persisting while layout changes.
Or use room properties again. The Photon objects remains the same during layout changes. So you can keep state in room properties if you are in the same room while switching between "Selected Level" layout and "level".