Is it possible to plug in an external monitor to the HDMI port and use it with a mouse to select items and control lights?
It is possible to plug in an external monitor and use it for show file feedback. This is done by navigating to Setup > Settings > Console and enabling External Monitor mode.
However, there is no way to get a mouse onto that screen since use of a mouse is not currently supported on this console. The External Monitor mode is a static view of show file information that remains the same as you navigate the touchscreen.
With regards to the display requirements you just need to make sure the display has provisions for HDMI.