So the sunglasses do have a significance.
Anything to do with vision is significant! They just did very little with them initially.

I think there is more going on between the Doctor and Ashildr then we are lead to believe.
Not sure what you mean by this, but will get back to it in my next review! :)

I'm still annoyed that Rose and Jack never had the chance to address his immortality.
Uh-huh. She never knew.