Regarding Dr. Strange for ToT... I'm going to preface this by saying this is Tinfoil Hat Handsome Pete talking, but it would not be an entirely new idea for a retheme of the DHS version.
The important part of the Marvel Universal contract is that Disney cannot use characters that appear in IOA or any character within the family that the character belongs to. The closest Disney has come so far to this is the Guardians, who aren't really Avengers because they're their own family.
But is Dr. Strange an Avenger now? In 2016 I would say no, but based on the role he's taken in some of the newer movies, I think it's a bit more debatable whether he is.
What's a good way to judge whether or not Universal thinks Dr. Strange is an Avenger? I dunno, maybe throwing him out on the streets unannounced for (what appears to be) a single night at a hard ticket event. No phone call from Universal complaining about that? Guess they don't think he's an Avenger ¯\_(ツ)_/¯
No inside info... I'm skeptical that ToT is actually on the chopping block but found that to be incredibly odd move for a holiday event.