3.
There is a scientific explanation as to why she is so lustful.
Bearing such a powerful mind put a lot of stress on her body and finding a proper release is difficult.
There most likely are some psychological or subconscious reasons too but those can be discussed later.
2.
At the end of the the worlds most powerful mind simply heads home and does whatever she can to relax.
During the day she is cold polite and poignant though when at home she is more open and relaxed