The red eye thing definitely factors into being a Greenseer, as Leaf tells Bran in ADWD, and Euron tells his brother that he used to have dreams that he could fly as a child. But I think more than likely Euron is a fallen protege of Bloodraven rather than still in his employ. He got to close to the heart of winter and the Night's Queen got into his head, so Bloodraven had to go with plan B and use Bran.
Doubtful. Dragons have historically fared poorly in battles where water comes into play; During Aegon's Conquest Meraxes was unable to be properly utilised in the taking of Storm's End because the rain was too heavy for it to fly or breathe fire. During the Dance of the Dragons the Tyroshi fleet managed to kill both Vermax and Stormcloud by taking advantage of the aquatic conditions and using whaling techniques to bring them down.
Dany would want to hope that it's a bright, sunny, warm day at open sea when she faces Euron's fleet. But given that it's Winter...
Marie Claire: Do you color your hair for the show?
Sophie Turner: I do. I'm naturally blonde, so [right now] this is like fading auburn. I like the auburn.
http://www.marieclaire.com/celebrity/a9822/game-of-thrones-interview-sansa-stark/
I believe they are for her film Huntsville. From yesterday:Those tats are for a movie I think