Emile,
Thanks for stopping by our forum!
Yes... you should be able to replace on/off switch with a keyswitch. The hard part will be finding a keyswitch that fits inside the square opening in the frame (most keyswitches are round). You could make an adapter of some sort, or move the switch entirely.
As far as setting up the scooter to go faster, I've heard about people upgrading these scooters to 36V. But I can't say for sure if the controller will get blown or not. If it does, you'll have to find a 36V contoller (maybe the one from the EZIP E-1000). You also have to consider that there's nowhere to place an extra 12V battery to upgrade to 36V...