Power Sex Suicide: Mitochondria and the meaning of life by Nick Lane is a good pick. It isn't entirely biochemistry, but does delve into the electron transport chain and metabolism. It is also packed with interesting stuff.
No. There is a very entertaining and informative book titled Power Sex Suicide by Nick Lane which describes the many roles and functions of the mitochondria. Lane spends several pages detailing the discovery of the mitochondria in cells, and the rigorous efforts by several researchers to isolate and culture mitochondria from cells. Ultimately every attempt failed. The mitochondria are incapable of living without the support from the cells that contain them.
It is possible to isolate mitochondria from cells, and study (some of) their function(s), but you are limited to about 12 hours (at the extreme) before all mitochondrial function is lost.
We just went over this article yesterday. But yes, we get faster because training produces oxidative stress in our muscles, and *anti*oxidants take away that stress.
FYI, high doses of vitamin C were originated by Linus Pauling based on no evidence. He was still one of the most brilliant men who ever lived, and his book General Chemistry helped me through school since it was written better than a lot of textbooks, and I still refer to it often (which is pretty good for being published in 1947). But he was wrong about vitamin C, as brilliant people often can be wrong when working outside their field.
Antioxidants were actually proved in the early 90s to be ineffective at preventing aging. A very detailed rundown is given late in this book.