Darn, I had a big response typed out and now it's gone
To sum up, make it clear (in letter/email form always works best for me) your expectations. Say in no uncertain terms that food must be finished before coming into childcare, and children must be dressed and ready for the day as to not interfere with your childcare routine. I would also address the little girl's aggressive behaviour and positively suggest to "to work together" to create a more peaceful atmosphere. If after a week, things aren't changing, buh-bye.