There’s a Colin Firth interview in Taiwan’s LOOK magazine. In this interview they asked if Firth learnt something unexpected about Harry in the second movie. Here’s a summary of what Firth said:
I found it interesting that the audience knows nothing about Harry. It was decided during the first movie that we did not provide any background information about Harry. There was no mention of his parents, his education. We don’t even know whether he’s British, whether he is gay and whether he’s married. Nothing, we made Harry a mystery. Then in the second movie, we will learn more about Harry. Harry will reveal information about himself a bit.