Question: In one of the flashbacks, after Kristy put the magnets on Michele's back, why did she eat Romy's hamburger? This just struck me as odd since the "popular girls" in movies are usually portrayed as dieting often, and they usually don't eat the junk food that the non-popular characters eat.
Answer: It was a way of her showing Romy that being popular (in high school) comes with "power" over the less popular students and ability to do what she wants without fear of retribution. Conversely, in order to try to be liked by a popular student, a less popular student will yield to the popular student and/or give (let her have) anything she wants, including her lunch. [It doesn't always work this way.].
Question: When Romy goes to what I'm assuming is a dating agency, the lady she speaks to says to her something along the lines of "try VH1", what exactly does this mean?
Answer: She tries to get on a dating show that airs on MTV. She is over the age limit for contestants and the lady tells her to try VH1 as a joke.
Answer: She ate it because she's a bitch and wanted to hurt Romy. She didn't take it to eat for food.