Another great cliche idea! It's a nice plotdecide, but it doesn't make much sense.
I do have to admit, Salazar having a private library somewhere is not that big a stretch, though I suppose it would probably have been found and placed in the Restricted Section... Not mentioning the fact that it'd be a bit outdated...
One cliche that bothers me is the 'Potters are billionares' thing... As someone once pointed out to me, the Wizarding community of Britain is not that big... there'd be no reason for so much money to even be in circulation let alone in the possession of one family. (Do the other countries have the same currency? I can't remember...). And even then, who says the Potter's were old and wealthy?
One other one: Harry has been accused of being crazy and a Dark Lord several times... I'm surprised some slander and dark looks have been all that he's subjected too...
Hope these give you some ideas to work with!
One thing though: chapter 1 has a spellingmistake: Animangus instead of Animagus.
Hope you'll continue soon!