I disagree with Because of the horcruxes, Voldemort was never dead. He only used the potion to give himself a proper body again. Like Dumbledore says, no spell or potion can bring back the dead. The one about Ron and his journal is so cute!
I must disagree on the "fact" about the dementors. On page chapter one of Harry Potter and the Order of the Phoenix, Fudge states "That's right. And they're [the dementors] breeding. That's what's causing all the mist.