We do not know. There will be a focus on cutie marks, but that does not guarantee the CMC getting their cutie marks. The episode's synopsis refers to Apple Bloom's anxiety over getting her cutie mark, but this does not necessarily mean she will get it, since such anxiety has been explored in previous episodes. The episode may simply teach a lesson about patience or not worrying about the future.
Neither Apple Bloom, Scootaloo, nor Sweetie Belle get their cutie marks in this episode.
Season 1, Episode 1: Friendship is Magic
Yes, the My Little Pony Friendship is magic episode Twilight's kingdom is involved in the rainbow power.
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.
My little siblings watched Babycakes and I thought it was cute.
No. It is the last episode of season 3, but there will be a season 4.
This episode has already been released.
Photo Finish is in season 1 episode 20 "Green isn't Your Color"
Castle Sweet Castle
Yes. This has recently been announced.
No. Justin Bieber was never cast for the television show My Little Pony: Friendship is Magic.