Agamon said:
I have so many questions about the physiology of Karen's body. But many of them are not meant for polite company, or ENWorld...
On Karen's physiology, while keeping it polite:
The nanites do help to explain some things

Karen's body is still slowly evolving. When she first changed to crystal, the nanites reacted to her wish to become invulnerable literally and instantly changed her cellular structure to crystal. Afterwards the nanites began fine tuning her body to what their host wanted while working with what they already did. While other Elites develop new powers, Karen is slowly becoming more human again.
At first she was in essence a moving rock, unable to keep food down, drink would run right through her and she couldn't sleep at all. Her heart had stopped and blood didn't flow through her veins anymore. To keep her alive the nanites had to develop their own powerful energy source or she would become nothing more than a crystal statue. Over the past year her heart has begun pumping her blood again, albeit very slowly. Her natural cycle has started up again and could get pregnant, within normal Elite limitations. She could eat and drink again, if she wasn't afraid to try it, though she wouldn't gain any energy from it.
She started to take birthcontrol after she and Kal had their chat about babies. She doesn't know if it works, or is even necessary, but she figures better safe than sorry.
Hope this clears some stuff up
