First, she is 16, she doesn't need a bedtime and certainly not 10:30 on a weekend

Second, like you said, there are a LOT of changes in her life and the only constant she has right now are her friends-keeping in mind that 16 year old girls are VERY social and will have no friends in her new school (unless she is still going to her old school). I don't see why she couldn't go somewhere for Halloween-it isn't like it happens every weekend. I would let her go but tell her she needs to by home by 11:00. I would also compromise and let her go back every other weekend to start. Eventually the length of the trip and meeting new friends will kill her desire to go back to see everyone all the time. I would also add her to your cell phone plan so she can keep in touch with her old friend AND so she has a cell phone for those long drives. I would also install Skype so she can chat with her friends. Honestly, it sounds more like a prison sentence then a home from your posts.
As far as breakfast goes, maybe she just isn't hungry for breakfast. I can't eat right away when I get up and our DS18 is the same way.