For those questioning Twilight's wings, I'll paste a comment I left down below, in response to ~widsithgrey
, that might explain it.
I don't think normal ponies would live quite long enough for [Twilight] to still be alive as her normal self, after Spike has matured and (presumably) slept for 100 years. I wanted her to be there when he was waking up, though, so I decided to go with the ever popular idea of the mane six gaining extended lives and turning into alicorns. Or Twilight, at least.
Especially after the latest episodes. Celestia said Discord ruled before she and her sister (and maybe the holders of the other elements? who knows) gained control of the elements and trapped him in stone. Now that Twilight and company have the Elements, I quite like the idea of them ruling after Celestia.