Ian McKellen isn't in any of the Harry Potter movies. You are probably confusing The Lord of the Rings movies with the Harry Potter movies. Ian McKellan plays the wizard Gandalf in The Lord of the...
Um, a Hogwarts uniform. Just like every other student in Hogwarts. However, in the scene where she kisses Ron, she is wearing a long sleeve light pink shirt and dark pink skirt.
Not known because she was bitten by a werewolf in the battle at Hogwarts, thus she either died from the wounds, turned into a werewolf or recovered from the wounds, but her fate after that is...