Recently interested in machine learning, and I want to use it to help people.

I don't really know anything about the state-of-the-art of machine learning, so keep that in mind while reading.

It seems like there is a lot of work that can be done in applying machine learning to medicine and biology. I want to know how close we are to being able to apply these techniques to helping people directly (i.e. through healthier/longer lives). I also see things like self-driving cars as a step in this direction.

I have a strong programming background, but only a BS in Math from a mid-tier state university.

I just want to know:

1. Are there enough people working on these problems? (I think the answer will always be "no", but in terms of the number of people able to contribute significantly)

2. Are there subfields/related areas that are making more progress than others?

3. How can I get started, given my background?

4. Given my goal (helping people live longer/healthier lives) is machine learning a reasonable approach currently?

Here is what I am doing currently:

1. I've started working through Bishop's Pattern Recognition and Machine Learning, this has been slow going, but is very interesting.
2. I am currently working on different solutions to the beginner Kaggle competitions
3. I've finished Andrew Ng's Coursera course (which is what piqued my interest, but is obviously lacking in depth)