Yes I think 3Ts has got it right.
Remember that 17-22 year olds have recently undergone 12 years or so of education, and many of them will have passed through the State system. Of course the teachers' unions (and by implication most of their members) believe that Mrs Thatcher was the Great Satan and are still giving the impression to their charges that for twelve years she arranged the systematic slaying of all the first-born children north of the Watford Gap. They also allow their pupils to believe that the Tories hate all poor people, would prefer they did not exist and that their policies towards the less well off are not dissimilar to those that Hitler held towards the Jews.
On a more practical note few 17-22 year olds are self-sufficient and none of them have ever lived as an adult under a Labour government. None of them have any inkling what it is like to be declared "well off" and are thus ripe to have your pips squeaked when in reality you are just about holding your head above water. Very few of them know what it's like to get out of bed before 6am each morning to go and earn a crust and pass by your neighbour's house whilst he's still in the land of nod having all his expenses met by the taxpayer. When they grow up they'll learn about these things the hard way.
The reason why they think that Europe, the HRA and immigration are all good is simply because they have never been told otherwise (see above for reasons why) and have not yet had a chance (or the inclination) to think it through for themselves. That also, of course, explains why UKIP holds no appeal to them.
I really cannot imagine why, despite all this, most of them would prefer to retain the monarchy.
Every generation elects a Labour government once in their lifetime. They always think "things can only get better" under such an administration. Unfortunately for the rest of us it means we have to suffer the results of their folly for a few years until they discover the error of their ways.