I'm using her in Skyrim and had difficulty.
Is she Altmer?
Yes, she's an Altmer, but I don't remember her appearing in the Alliances cinematic trailer.
I don't know who she was, just a commander I guess. She's an Altmer. The other two aren't faction leaders either, in case you were wondering.
http://static.elderscrollsonline.com/assets/img/cms/media/wallpapers/47b71a82c20dc0bd64.jpg concept art of Ayreen.
I wouldn't worry too much about skin tone. She resembles a human much more than elves normally do, so I assume it's just for the sake of the trailer - in reality her skin is probably more golden.