For the higher level Italian, there are three sections.
Section B, that has 3 choices (unseen, prescribed novel, and essay on prescribed text) if I choose to do the unseen, does that mean I won't have to do the essay on the novel? Is there more reward for students who choose the novel, because it was prescribed?
You only have to do one, so if you choose the unseen you won't have to do the two prescribed questions. There's 60 marks for each, so there isn't any extra reward for doing the prescribed novel. If you find it easier to do the unseen, then go for it :)
I would still read one of the novels prescribed, just in case the unseen was extremely hard on the day or something, but the choice is yours for that question :)