Where can I find a content outline for the MCAT?
You can find a comprehensive content outline on AAMC.
Related articles:
MCAT Facts || Changes to the MCAT in 2015
Should I take all prerequisite classes before MCAT?
There is no set answer to this question. Taking all your prerequisite classes prior to the MCAT is definitely an advantage because then most of the material on the MCAT will be review. Nevertheless, you can learn the material fresh through a MCAT course or by self-studying. It is your preference, but MCAT takers typically take the MCAT after they finish their medical school prerequisites.