You just plug the cable into the car; the system knows the car's VIN and charges the card on file. There is no smartphone required. It's a nice, seamless system compared to the competition.
The population of electric cars drivers without a smartphone must be low enough to ignore them.
No and no. But they are opening them to non-Tesla cars by providing an adapter. For this, you pay with your credit card via a smartphone app.
Seems like they could easily offer some kind of gift card option.