YES
yes
The charger is a standard cell phone charger, so the stated output is 5 volt at 1amp.
I wouldn't leave it closer than 2 feet to an actual heat source & you should be safe?
Depends on which mode your using... but on brightest mode mine would last about 3 hours continuous
It can be charged with any USB port. The original A/C adapter is 5V 500mA.