As others have said:
1) The balloon was caused by approaching and landing too fast - what speed were you doing?
2) The uncontrollable pedals - welcome to nose-wheel 'shimmy' which has occured in every 172 I've flown when it's been too fast on the ground - be it landing or even taxiing. When it happens on landing you've got to get those controls back into your stomach to take the pressure off the nose wheel. Being firm on the pedals is just putting more strain on the nose wheel leg.
Less speed in this case brings more finesse you'll find.