I would say just a phase, keep up with discipline and consequences, btu also remember to reward GOOD behavior. As for cutting her hair, I would take the hint and talk to her about why she keeps trying to cut her hair, ask her how she would like it to look ( how short, what type of style) and maybe use the incentive of going to the salon for a big girl hair cut as a reward to a certain amount of good behavior???
As for the stepping on a boy's feet because he was being annoying - what exactly was he doing? - he could've been hitting or physically annyoing her....explain that is not he right way to handle it - and that she should tell the teacher if anyone is being annoying, not take it into her own hands. As for touching butts - talk about private parts ( anything covered by a swimsuit is a private part) and that we never touch someone else's or let them touch ours.
As for snotty attitude and not feeling bad about misbehavior, she needs consequences to make her feel bad at this age, she obviously doesn't understand yet the intrinsic "naughtiness" involved/why she shouldn't do it.
If it were me, I would try to get her to focus more on what she SHOULD be doing, keep her busy with chores and accomplishments and rewards....make her a chart where she can earn stickers or checkmarks or whatever for doing good things, things she can do at her age include: feeding and watering the pets, setting the table, emptying the dishwasher, making her bed, folding laundry, putting away laundry, cleaning her room, dusting....and as she earns those reward symbols, stickers or whatever, make a scale of what kind of bigger reward she gets at the end of the week in exchange for whatever number of stars earned. You could also take it a step further - make a list of common misbehaviors ( mouthing off/attitude/sass, hitting, kicking or otherwise hurting others, trying to cut her hair, damaging toys or other belongings, losing things, not finishing homework), and how many stars get taken off her total for each misbehavior. Then at the end of the week, tally up the total, explaining what she wouldv'e gotten for all the good behaviors, and what she is going to get because of the removal of rewards for the bad behaviors.
Good Luck!
Jessie