Steven Moffat at Comic Con promises answers to at least some dangling questions like who blew up the TARDIS and what the Silence were up to. Maybe not those particular ones, though.
He also mentions his reference to the Valeyard, and questions just how dark the Doctor could really go.
“But you know, he’ll only ever get so dark, let’s be honest. He’s the Doctor. I think a man who worries about going bad is never really going to go bad... Maybe not.”
Of course, the Valeyard first appeared at the end of the Sixth Doctor era, which sometimes went None More Dark in a “is this really appropriate for kids?” kind of way. If the Valeyard turned up during the Moffat era he’d probably be rather whimsical, and almost certainly less scary than Six was himself in Revenge Of The Cybermen or Vengeance On Varos...
Not that the Doctor can’t be a bit off-putting at times, but we’re not talking Sapphire And Steel here, you know? Even his most berserk alien-atomising rampages are relatable.