A second battery is recommended just to make sure you don't run out in the last class of the day
A "DisplayLink" USB-to-VGA adapter costing about $70-$80 will allow you to connect to a projecter. See
http://www.entourageedge.com/forums/...ht=displaylink for some example models.
For keyboards, any USB keyboard will work. If you're interested in as small a keyboard as possible that's still practical to use, look at
http://www.entourageedge.com/forums/...d-for-the-eDGe.