The famous empress wannae Queen of Solitude, is she a Dragonborn ? During the fight with her, she uses a shout, but as a spirit shouldn't she be insta devoured by us ? And what "type" of dragonborn is she, alessian or dovah ? Can someone clarify this for me ?

You don't have to be a Dragonborn to shout. Potema was a powerful necromancer, not a Dragonborn.