Press the left button 2x at the bottom right, select Energy control in the menu that appears and then Room lighting. Here you can adjust the light or switch it off completely.
With this monitor, the frame rate cannot be synchronised with the GFX.
Depending on the game / genre / scene, there is clearly a difference between synchronised frame rates between monitor and GFX versus non-synced monitor & screen.
On the back of the monitor in a vertical position, just behind the stand.
If you look on the Internet, you will find pictures where the ports are visible.