Great way to re interpret canon. Many of the things Snape thinks are the same things I thought when I read Deathly Hallows. I don't think Dumbles came of as quite the hero Rowling wanted because he truly did put children in harm's way (most especially Harry). I never understood the need to find the Horcrux's first. I mean at least if they killed Voldemort's body, it would take time for him to become corporeal again and only if he found someone like Quirrell and Pettigrew). They could have then searched for the remaining horcuxes in relative peace.
I really liked how you handled this - and that Snape and Harry became comrades if not ezxactly friends right away.