Actually, I'd recommend to ensure that the battery is full. I think if the flashing was interrupted and thus the mobile didn't work anymore, you could repeat flashing and it should work, but I haven't tested that and wouldn't recommend it at all!
The CSC is in the mbn (?) file, there are several CSC's to choose from. Look in the Developer forum, there are also CSC that are already interop-unlocked!
For installing the driver, you need to turn off signature checking. You do that by booting Windows 8(.1) and pressing F8, then search the option that temporarily disables driver checking.
Hope everything works fine!