So when it powers off, it goes into a sleep mode. That sleep mode doesn't require alot of power, but if you have it set to turn on if the camera detects vibrations, it uses the cars battery. Mine is plugged in all the time and it only powers on when I turn the car on or it feels vibrations. With the vibration setting, it will turn on when I open my car door. But if your power source isn't powered when the car shuts off, then it doesn't use any power, just what the camera has stored up. Hope that helps 

Yes …. You can use anywhere it goes with you… I use mine in our camper 

Yes it will 

I agree with eddie - I have not really needed to support the 15 pounds that it should handle. With my camera with battery grip, 135mm lens and hanging my camera bag with extra body and 3 other lenses from the hook there was no visible deflection on the tripod legs and made it super stable. Any DSLR with standard screw mount should work without problem. My canon 70D had no problems. 

As long as the lense is 67mm it will work