Why is charge the same on every capacitor in series?
Charge cannot be created or destroyed.  Since you only have one possible current path through all the capacitors (and current is just flowing charge) the charge on all 3 capacitors has to be the same.  The capacitance of the capacitor indicates how much voltage a particular amount of charge corresponds to Q/C = V.  Put more charge into a cap, get a bigger voltage difference.  Put the same charge in a smaller cap, get a bigger voltage difference.  So what happens in your circuit is that the charge is distributed evenly, but the applied voltage is distributed according to the capacitor sizes, with the smallest cap ending up with the largest fraction of the applied voltage.