Leonardo Da Vinci's work

I heard that after checking the layers under the Mona Lisa they found out that the sketch for the painting was Leonardo Da Vinci's self-portrait. Is it true?

Dr. Lillian Schwartz of Bell Labs suggests that the Mona Lisa is actually a self-portrait. She supports this theory with the results of a digital analysis of the facial features of Leonardo's face and that of the famous painting. When flipping a self-portrait drawing by Leonardo and then merging that with an image of the Mona Lisa using a computer, the features of the faces align perfectly. Critics of this theory suggest that the similarities are due to both portraits being painted by the same person using the same style. Additionally, the drawing on which she based the comparison may not be a self-portrait. See the next link : 

http://www.lillian.com/

I also heard that he was gay, is it an insubstantial assumption or a based one?

Beyond friendship, Leonardo kept his private life secret. He commented "the act of procreation and anything that has any relation to it is so disgusting that human beings would soon die out if there were no pretty faces and sensuous dispositions".

Leonardo appears to have had no intimate relationships with women beyond his friendship with Isabella d'Este. However his contemporaries represented him as a passionate man, and all his life he surrounded himself with beautiful young men, at times even getting into scrapes with the law over his alleged erotic flings with males. His relationships with his pupils Salaino and Melzi, first taken on in their mid-teens or earlier, are widely considered to have been passionate, not least by Melzi himself. His love affairs with young males reflect the cultural milieu in which he lived, where pederasty was widely practiced by men in all walks of life.

http://en.wikipedia.org/wiki/Leonardo_da_Vinci%27s_relationships