A Ph.D. like all degrees has very little to do with genius. It is a signifier of your ability to work independently for long periods of time (3-6 years), and adapt to changing circumstances. This is the kind of aptitude that employers in nearly any field look for. A high schooler, even a genius, remains unproven in that area. This is why many genius people don't get any degree's yet companies still like to hire Ph.D.'s (even though most of them are not genius).

Yeah, as a Biology Ph.D. I have watched many of my friends go into finance and consulting and a number of other fields. No one gives a crap what your Ph.D. is in. They will look at your publication record (academic jobs) or just interview you to asses your specific skills/reasoning abilities.

Actually efficiency is the fallacy. Because of the huge latency involved in CO2 emissions (what we put up now will be there for ~100 years), the burn rate doesn't matter that much. If we use all of the fossil fuels available it will be the end of the planet as we know it. Whether we draw it out over another 50 years because of increased efficiency doesn't really matter. Increases in efficiency combined with transition away from fossil fuels is the only way to go.

No large long term studies have been done. The short term effects are pretty much what you would expect (a shift in blood and urine pH). Read on: http://www.ncbi.nlm.nih.gov/pubmed/20836884