So far it has not been stated. Given that there are six keys, it is most likely that each of the six main ponies will have an episode in which she finds a key.
There are 26 total episodes in the fourth season of My Little Pony: Friendship Is Magic.
Yes. This has recently been announced.
That is unlikely. She may become temporarily incapacitated or briefly appear to be dead, but remember that this is a children's show, so the writers would have a hard time getting away with killing one of the characters.
Yes, Princess Celestia, Luna, and Cadence will get their magic back since the main 6 defeated Tirek and have been rainbowfied to help Equestria receive their magic back. If you want to watch it you can on Youtube or Dailymotion
Not much is known, but it has been rumored that she is Princess Cadence and Shining Armor's daughter.
Yes, Cadance will appear in the My Little Pony Friendship is magic episode Twilight's kingdom.
The My Little Pony Friendship is Magic Rainbow Power toys are connected to the box on the Root of the Tree of Harmony show.
Most likely
No, that box transformed into castle
Yes, the shining armor will appear in the My Little Pony Friendship is Magic episode twilight's kingdom.
No, it has never been announced or in any way suggessted that Justin Bieber will appear on the television show My Little Pony: Friendship is Magic.
My Little Pony Friendship Is Magic - 2010 Friendship Is Magic Part 2 Elements of Harmony 1-2 was released on: USA: 22 October 2010 Italy: 31 August 2011 Poland: 15 October 2011 Ukraine: 28 January 2013 Japan: 9 April 2013
S2 E1 "Return of Harmony"
No. She does not appear.
yes
No. Justin Bieber was never cast for the television show My Little Pony: Friendship is Magic.
My Little Pony Friendship Is Magic - 2010 The Return of Harmony Part 2 2-2 was released on: USA: 24 September 2011 Ukraine: 1 July 2013 Japan: 8 October 2013