Toddlers of that age do seem to have an overwhelming "it's my world and my way" attitude. If anything challenges that they can't cope and flip out. Regardless of what the situation may be, if it's not fitting in exactly to their agenda they will react. Also at that age, they have very little control over their emotions....in particular anger it seems so once they loose it they can't seem to regain control over themselves.
It might seem silly or irrational to adults but it's the end of the world to the toddler!
It's not easy and on the whole these things usually are phases.....try not to get too upset, stressed and angry over it as you don't want to show her that anger is the answer. She is still young so I don't think explaining coping strategies etc would work but she does need to understand that she can't go around pushing and biting other children. If she's doing it at nursery as well at home then you and the staff need to come up with a form of punishment/wasy to deal with it that can be done both at home/nursery/out etc if she does do something like that.
As for the changing thing I'd definitely bring it up with the manager as it's a form of neglect. If the staff you've spoken to workers already and they've not acted you need to go to the next level.
