In response to the first question - I would argue that the moral justification is with local government. More people voted for the provision of caring services in determining the make up of their councils than voted for economic restraint in determining the make up of the government. Indeed the services first argument can be seen as having achieved the greater share of the vote at the general election too, hence why we have a coalition government. This would imply therefore that the mandate being claimed for cuts is not as outright as suggested, thus PSRs main premise is incorrect.
The second question is an interesting one, especially since the recent police request to avoid cutting their budget so that they can enforce cuts by crushing protest in other services and sectors. So much for solidarity! As a nation we appear to lap up the media view that protest is bad, but then expect grass root movements abroad to rise up and topple elected regimes that we disagree with. We applauded, funded and supported the Solidarity movement, enabling Union freedoms to win victory over the oppressive and elitist Communist system of the USSR, yet condemn our own Unions for defending pay conditions and safety in the UK.
I would say that direct action is acceptable where to take no action would lead to the greater harm or detriment. Personally, I will consider direct action where I see financial or social harm against the majority, such harm against the minority where alternative actions can achieve fairer outcomes, or risk to safety or life.
For the third question, absolutely. Like them or loathe them a Trade Union is a regulated entity with a clear and published agenda, supported by its members. Where interests with government are at odds then opposing the government is justified. The likes of Murdoch, whilst successful and with a massive readership (happily recieving their free CDs, bingo-lotteries, and other incentives) has only his own business and personal interests. Such disproportionate wielding of power is at odds with democracy and risks peverting government.