Your hoverboard will come with a charger than you can plug into any US power outlet.
No, your hoverboard will stop moving forward on its own when you fall off of it. HOWEVER due to the round shape it WILL CONTINUE TO ROLL if you were moving forward when you stepped off. It is important to stop your hoverboard completely before stepping off or run after it if you fall off while in motion.
No, they are very durable. However you should expect yours to get scratched many many times with heavy use. Scratches tend to show up more on colored and black frames. Thats why we always RECOMMEND GETTING WHITE. Unless your hoverboard gets run over by something quite larger and heavier than it (a car for instance) it will most likely survive any accident.
The number and variety of tricks you can do on a hoverboard is rather limited given the weight of the unit (the average hoverboard weighs 25lbs).
Generally speaking, yes. Most indoor locations will allow you to use your hoverboard. We use ours when we go to wal-mart, Costco or other very large retailers. The best use we have gotten so far is at the airport because it is large, open and requires lots of walking.