1. Its not so much they're committed to austerity as a ruling policy.
They appear to have no other choice. They bluffed their way into the Euro which in doing so gave them access to funds which were largely used to inflate their public sector reducing unemployment in the process. That was all well good other than the fact the loans needed repayments which they were progressively unable to make partly due to an apparent inability to collect taxes. Much of the most recent bailout at lower rate of interest was used to pay previous debt at higher rate. The bailout was conditional on ability to pay and it is that which continues the austerity measures.
The alternative was that they folded and left the Euro and possibly the EU too. Given the choice between that and austerity its up the to the Greeks which they should choose as there seem to be no other viable alternatives. Its foreseen that if the former were to occur it would take c.20 years for Greece to return to anywhere close to its former state.