Im just trying to picture how this will go, she will be rude/annoying to her friends, but not to other guests. When it comes to line cutting, she has to make sure she is the last of the group of friends, but goes in before the next group regular guests. That will give 2 seconds of fun, I guess?
Same with the iPad, as soon as everyone is ready to see the show and fireworks, she can then hold it up to block the view of her friends, but as she doesn't want to be a real rude guest, she will lower it after a few seconds. Sounds like fun. I have no idea how this is going to be a nice evening for anyone.
For things to say, which she can only say for her friends to hear, then we don't have a 'things overheard at Disney'-thread in a few weeks, I would go for complaining why lines are long, why are there so many people, no fastpasses, disgusting food, where is the Harry Potter ride. Someone who has no idea where he is and what Disney or theme parks are about.
But reconsidering this might be a better idea. Having a negative attitude and spreading negativity all evening is hard to keep up and might result in actually annoyed friends. Do the other friends know that this is her plan or does she want to surprise them?