I was born with a myriad of mental issues ranging from psychosocial-immaturity, ADHD, sensitivity to noise and various other factors that correlate closely with Asperger's syndrome. My dad is PhD in Physics with a focus in cryogenics and my mom is a French existentialist artist (weird childhood...
Exercise shouldn't affect your studies negatively, Proton Soup is correct in that exercise will help brain functioning. Also lifting and exercise is an excellent way to relieve stress, allowing you to focus more on your studies, perhaps?
Avoid steroids or testosterone boosting supplements!
You decide to pick up a pen through various cascade pathways, you gather sensory information via afferent neurons, see pen, then your brain will send signals to your motor neurons, causing you to pick up the pen. Very very brief explanation, if you want more detail check out...
You don't need a nucleus or DNA to have already been evolving, for example, certain viruses only contain RNA. I would suppose evolution began with the first self-replicating organic molecule, most likely some ancient protein.
we could always ask Carl Sagan, if you wish to bake an apple pie...