well, adding a battery would definitly help with the speed and torque, but not the distance. i am not sure what the additional voltage will do to your controller though, let alone "the lights and things". some controllers can handle the additional current and voltage, but some dont like it at all, so if you want to try it that would be up to you, or you can find a 36volt controller and run it like that, change out the "lights and things" and leave the motor 24v and you will be zipping around in no time.
FREE is always better.Speed, Distance, Torque... Pick any 2