#1) Did Mark Zuckerberg really call his girlfriend a bitch while creating FaceMash.com?
Yes. Screenwriter Aaron Sorkin used an actual trasncript from Zuckerberg's former LiveJournal Blog (down to the HTML code) for the movie.
#2) Does Erica Albright, the girlfriend character Rooney Mara played in the film, actually exist?
Apparently so, but her name was changed in the film. The real name that Zuckerberg mentioned in his blogging was Jessica Elona, but she has never been interviewed or heard from… ever. Which, honestly, is a little strange. It's unknown if she is a real person, or if Zuckerberg and her were actually dating at the time, but Zuckerberg did definitely say it in his blog.