1. that's impossible, because if the bullet penetrates everything, it will also penetrate the armor, and if the armor stops everything, it will also stop the bullet; so they can't exist at the same time, because one would cancel the other.
2. he must drink some of it before drowning.
3. No. Mission accomplished.
4. She would still be there, but at the wrong time, with no parents or identity. Pretty sad for her.
5. You can just convert to kelvin, calclulate and convert back, technically it will be twice colder, or rather half as hot.
7. Light going in the same direction (that of the car) would be trapped at its source, light going in any other direction will be reflected until it is completely absorbed by the headlight's not-infinitely-reflective surface.
8. It's essentially the same as the perfect bullet/armor question, if he can't lift the stone, he is not almighty, and if he is almighty, he can lift the stone.