Returning Baddie for 50th Anniversary

According to one reliable source, Omega is returning for the 50th Anniversary. No actor has been confirmed to play the role of him yet. They could just be keeping it a secret (they managed to keep Jenna-Louise Coleman's appearance in Asylum secret) or it could be someone we already know about.

The classic series actors have all denied involvement in the 50th anniversary. I frankly think Moffat isn't stupid enough to not include them in the episode. I think either Davison, Baker, McCoy, or McGann (or some combination thereof) is going to play him. How? In the 1983 episode The Arc of Infinity, Omega stole the Doctor's biodata and duplicated him in order to create himself a body. He may still have that biodata and may be using it for another body (his original one was destroyed in The Three Doctors).

If it is a new actor, it's not going to be anyone we saw in location shooting. The BBC is going to want to keep it a secret, so all of his (or her) scenes would be filmed in Roath Lock studios. They're keeping everything very hush-hush, so we'll likely not get any new casting details for months. The only cast the BBC's announced has been those who were location shooting, and only then right before the actual filming. They're revealing as little as possible, but keeping all the glory of the announcements to themselves.

My Theory For the Question, Series 5, & Series 6

I already posted this theory a real long time ago here, but I'm posting it again where it will hopefully get seen more, plus I'm expanding it a little.

The Doctor's name is the passcode to open the Time Lock on Gallifrey. The Doctor chose it because it's only known to a handful of his family and friends. Once the war was over, he was the only person left in the universe who knew it. The Time Lords couldn't open the time lock because (I'm just making this up) a time lock can only be opened by the device that created it. They didn't have access to his TARDIS, so they couldn't open it.

Well for whatever reason, Captain Jack has decided to open the time lock on Gallifrey, and he knows he needs the Doctor's name and TARDIS. He realizes that the Doctor isn't about to just hand over the information, so he decides to ask him on the Fields of Trenzalore, when no living creature can speak falsely or fail to answer.

The Silence realize that someone is going to try to open the time lock, and they want to prevent this. Their first thought is to kill the person who's asking the Doctor his name, but they can't do this seeing as it's an immortal. Their second attempt is to blow up the TARDIS. They fail to realize the consequences of blowing up a TARDIS, or perhaps they don't do it properly, and end up destroying reality and the Doctor has to reboot the universe. Their final attempt is to just kill the Doctor, which they try to do multiple times, and fail.

The only other person who could possibly try to open the time lock is Omega, safe and sound in his antimatter universe, where the Silence can't reach him. That's the only other possibility for who could be asking the question. It can't be the Master, because he must surely already know the Doctor's real name (they were probably friends before they chose those names). It can't be River, because if the Silence wanted to prevent her from asking The Question, all they had to do was not kidnap her, and just let her live a normal life. The only reason River knows the Doctor's name is because she was there when the Doctor revealed it.

Note that this a completely separate theory from this one.