1. Is there a large need for one? I know for me once I've traveled somewhere I can teleport back with little trouble.
3. The main use I seem to know about is to bring us back if we die. Of course that sounds preposterous as it is and it must be something like revival from a near-death state.
3. I can probably do the same if you can tell me how to. I admit these sorts of devices are rather different than what I'm used to.