Resolution: 640 by 480
Colors: 256
Refresh rate: 72Hz or less
While it is not necessary to bring a monitor, it's still a good idea to bring one, preferrably a 14 inch model. Having a monitor lets you face the audience while talking, which is more comfortable for the presenter. Also, the light from the monitor will help you see your keyboard.
If your normal resolution is substantially higher than 640 by 480, it's a good idea to finish by running the app(s) needed for the demo & moving them to the upper left corner of the screen, then closing them. Otherwise when you start the app(s) they tend to go to the screen coordinates where they were last time, which may be past the right edge of a 640 by 480 display. (Speaking from experience...)