Spanish monarchy

Topic: January 7

I was thinking the first topic for today would be the Spanish monarchy, which has been making news recently.
Here is a brief article regarding Princess Cristina and her involvement in fraud:
Spanish princess Infanta Cristina summoned over fraud
It also discusses the installment of King Juan Carlos in 1975, and his decreasing popularity. I would like you to explain: why was he (or the Spanish monarchy in general) installed? What is their role? Do you think they have shaped Spain's self-image or its international image? How are they supported (financially or otherwise) by the Spanish state?