1. I do not believe in the gaining of powers, per se. I think some people have a natural intuition or sensitivity to certain forces, but nothing that would ever get close to the science-fiction or fantasy level. As far as science goes, I think that with understandings of the brain increasing, it might be easier to train people better to use their minds, but again, I don't think it will ever reach the level of the stories and movies.
2. If we're going on the full spectrum of powers, I would love to have the ability to heal people. I have a strong aversion to pain personally and I hate to see people suffer.
3. I would heal people, of course. Though, such a resource would probably be in demand, so I'd have to find a way to protect myself, or at least keep my ability on the down low. I would be more likely to help the people who were either critical, or those who don't have the funds to get the best medical care. After all, I would only be one woman against the huge number of other human beings that are suffering...and I would probably spend my life with a lot of guilt over the people I didn't have a chance to save.
4. Since this is entirely in the realm of fiction for me, I don't know what I would do to get these powers. That's why fiction is so beautiful; it allows us to see life in another way, a theoretical way, and apply our own human natures to it.