For your name to appear on the screens in the waiting room, you have to have checked in first, (either online in advance or at the desk at staff travel check in) which you must do before 1hr prior to departure. If the flight is really quiet, you can be accepted and offered a seat when you check in on line but if that is not the case then you will effectively be placed on standby. Should this happen, then always go to the desk when you first arrive, regardless of if you have subsequently been accepted or not. Hold bags can be tagged at this point, which can save time later if you are accepted at the last minute.
Checking in online at the outstations can be a bit of a hit or a miss. Sometimes the flight can be wide open payload wise and you won’t be accepted in advance unlike Dubai. I think it is still worth doing as it can buy you a extra few minutes after the flight officially closes, should you be delayed getting to the airport.
Any apps which give the information you are wanting are restricted to EK staff only.
Hope this helps.