It's actually not the seat belt sign, it's the No Personal Electronic Device (PED) switch right next to the seat belt sign.
It's a small switch down on the Right Lower portion of the Weather Radar (WXR).
Can't help you there as I don't use the CoPilot or Checklist functions. Please post in this in the Copilot/Checklist part of the forum and the guy who writes that code (Hanse) will answer.
You won't know the Desent related information (which is really weather and runway based information) until you're ready for Descent, and even then it can change and might need updated. Simply enter the required information in the MCDU Approach Page.
Airlines Operational Control. Try Googling "Airbus MCDU AOC".
1. Download a P3D Flightplan created by SimBrief, PFPX, or any number of freeware applications that can generate a FSX/P3D Flightplan. Put the flightplan file in the Documents\Prepar3d Files folder.
2. Open ActiveSky, select the Flightplan Page, and Load the flightplan you created in Step 1 into ActiveSky. You may wish to ensure ActiveSky is in the Live Weather mode.
3. In MCDU3, insure that "Sim" is selected.
Thanks for your answer.
KSAN is listed on the Airport Enhancement Services (AES) Version 2.45 as well - see here. So just to sum up: This is the second airport that I found that is listed but in fact not supported by AES. The other one is Tromsø X - see this thread.