The villain for the season finale has not been revealed. It could be one of them, or it could be someone new.
No information has been revealed as to who the villain will be.
There is no known backstory for Queen Chrysalis as of yet, and it has not been confirmed if she was or wasn't Princess Papillon. Princess Papillion appears to have been a fan-made version of Chrysalis and so is not a cannon character. It is unlikely that Chrysalis has any connection with the Rainbow Kingdom.
Yes, Cadance will appear in the My Little Pony Friendship is magic episode Twilight's kingdom.
Yes, the shining armor will appear in the My Little Pony Friendship is Magic episode twilight's kingdom.
Yes, the My Little Pony Friendship is magic episode Twilight's kingdom is involved in the rainbow power.
It has not been revealed who the villain in Twilight's Kingdom will be.
Yes. The Villain in Twilight's Kingdom has been revealed to be named Tirek.
No information has been revealed as to who the villain will be.
It is not announced when promos will start. Such things are usually not announced.
Yes, the Twilight's kingdom from My Little Pony Friendship is Magic is the Rainbow Kingdom.
In all likelihood, yes. It has been mentioned that Twilight will focus her efforts on unlocking the mystery of the box, and no new episode leading up to the finale will center on Twilight.
no. and that rainbow kingdom is Cloudsdale.