Some people might have EV's and a J1772 would work for about all EV's. I don't know whats the plug but is it a J1772.
No. It is Tesla proprietary. J1772 only supports AC charging, AFAIK.
Yes, it is proprietary, but the car comes with several adapters for J1772, NEMA 14-50, and your standard 3 prong wall outlet.
The American/EU standard is (will be?) the SAE standard, but 0 cars have it so far. It is a hi-power extension of the J1772 standard (for which US & EU have different plugs!). CHAdeMO is the Japanese standard, and Leaf etc. currently use it.
Neither is powerful enough for the Model S, so Tesla did their own "standard".
Some historical data from way back in May, 5 months ago:
The Tesla Supercharger network is fine, but it may not exist where you want to go.
As they did by supplying a J1772 adapter to allow charging at stations using that plug, is it not likely that Tesla will make another adapter available to allow fast charging at stations which have the updated SAE Fast-Charging J1772 plug?