You can check my recent report on that flight here. It’s in French but Chrome will translate easily.

Indeed SkyTeam lounge available only if you are a SkyTeam Gold or Platinum.

To answer other questions:

• Left downtown at 1 but could have left later. There is little to no flights from SV terminal at that time of the night so security and custom are really quick. I had my hotel booked for that night so I slept about an hour from 11 to midnight (unless you want to linger in DXB for most of the day outside or in malls before heading to the airport or spend an insanely long time at the airport, I do recommend to have your hotel booked until your DoD)
• SkyTeam lounge was *empty* but food was plenty and staff was there doing their job.
• Because it’s middle of the night and no PAX, it’s the time they are cleaning a lot of stuff, which was ok but for instance the bar was not filled
• The airport has a bizarre feel where you see (landside) almost more staff than pax