2. since it is the fountain of eternal life, you would have to quickly drink some of the water, then you would never die in any possible way, not even drowning, however, if you did not drink the water and instead breathed it in, then it would go into your lungs and stop the circulation of oxydised blood, thus drowning you.
3. Easy, no, since you do not accept the mission, you do not have to accept to not accepting the mission.
4. Many theories suggest that if you go into the past and change something, you do not change the future, you instead make a whole new universe were the action you made is in effect. So the girl's grandmother would still be very much alive when and if she came back to her time.
5. There is no scientific "twice as cold", it is just a saying that something is considerably colder.
6. Since I am typing and not talking, you would have to have a voice recording to prove that I said something. IE. Yes (while SAYING no)
7. To you, the light would be going at the speed of light because it is a constant.
8. God make a stone and promises to never pick it up.