Ok... First of, you're spoiling the movie by giving away details of the ending in the topic, where's your manners?
Secondly, if you have the movie, then why do you have to "re-download" it? Seems really stupid to me.
Thirdly. Yes, thats the same girl. If you're going to watch again soon, why do you ask this? You're going to find the answer when you're watching the movie. Narratively speaking, the "eating-scene" wasn't weird at all. Also, she didn't "decide" to eat herself, she was an addict and couldn't control her behaviour once the myson drug had spread through her body.
There's not much to get here. It's a silly film. It has some good qualities but is definitely a STV film in both its category and overall mediocrity. If you want gore with a much more profound message watch the films of Shion Sono, Takashi Miike, or Kiyoshi Kurosawa.