Sounds like the most you can do is draw up a very specific list of acceptable vs. unacceptable foods. And then, can you document each time these "no" foods are packed? Start sending a notice home each time. Or speaking with her personally. After a little while, hopefully she just bends and packs appropriate stuff.
As for the other issues, it seems like she has a pretty abrasive personality.... no cure for that, unfortunately! LoL