Here is how it works, you stand in a Long Long line to meet the princesses, have a photo op, then go down where they come out on stage and do a show thing, some story telling, then the hair/et al. I would actually skip the line standing to meet the princesses and go into the area where they do the show, the CM will tell you when the next show is. You get a few photo ops after the show.
I would also skip the hair and go to Libby Lu.
Frankly, If we want to meet princesses we do lunch at Ariel's grotto, easier on the feet.