Run out of charge

Was on a 300 mile trip ysday and had my first range anxiety being down to 2 miles from being in middle nowhere and 2 broken hotel chargers. Taught me a few lessons.
Queries:
When it gets to zero will it stop?
Or do you get any extra buffer after that?

Mercedes help send you to the AA-
Do they provide a mobile charge (is there such a thing).

On the satnav if you dont have enough charge for final place, it sends you to next charger. But you cant tell if that is a house or a low voltage one. So I use zapmap. But how do you switch the charger instruction location off?? (So i can go the route i want, not to a charger).

Many thanks and apologies for being thick.
Ps only just found the 350 volt superchargers. Superb!