Somehow I seriously doubt that Ginny's going to keep her mouth closed and she may find that her employment with her brothers has been terminated as they have to depart to stay away from Dumbles; after all, owl-order can be done just as well from Canada as from Diagon Alley with their connections. I can see them moving while Lee becomes manager of the shop.
I rather suspect Snape is actually rather pleased by the turn of events, I get the feeling that his presence at Hogwarts was somewhat commanded by Albus given the information Albus held over him. I could see him quite resenting being forced to teach when he wanted to do other things. If he knows about horcruxes, I could see him passing the information on, esp. if a detente can be reached between him and Harry and they can talk to each other in a civil manner. I can just see Harry telling him about dealing with the basilisk in Second year and Severus blanching when Harry describes the diary and its effects, not to mention the gleam in his eye when he realizes he's got a comparatively recently-dead basilisk that can be harvested for potions components. I suspect he'd try and find out what other ones are out there as long as Harry agreed to "share the wealth" with the basilisk remains.