I'll go with the 'Black Captain' - Witch King of Angmar .
I believe it's Saruman the White (later Saruman of Many Colours).
That would be Saruman the White, who in the books becomes Saruman the Many Colored before having his staff shattered by Gandalf the White. A Maiar (demigod) and Istari (wizard), he was corrupted by the lure of power, and eventually died at the hands of Grima Wormtongue. Saruman was given the tower by the Steward of Gondor, Beren, in the year 2759 of the Third Age.
Saruman would capture him..torturer him til he gets what he wants to hear then kill him or keep him prisoner.
The white witch takes Edmund to her castle.
Lucy doesn't directly meet the white witch so probably doesn't have an opinion of her except it is related to the things the white which did to her brother. In that case, Lucy would probably hate her, as would susan
Edmund is at the Beavers' house and then he sees the White Witch's castle. He wants to talk to the white witch because he found out some things about Aslan that he thinks the White Witch would reward him for knowing. He walks very far to get to her castle.
aslan had an agreement with the witch
No street is given for the witch. Make believe stories often do not have real places or streets. The witch is the queen so I would say she lives in the castle.
Mr. Beaver is sure that Edmund has gone to the home of the White Witch because he noticed that Edmund's coat is missing, which is a sign that he has been to her castle since the White Witch would want to see anything from the world of men. Additionally, Mr. Beaver knows that Edmund has been acting suspiciously and has been tempted by the White Witch's promises of power, making it likely that he would seek her out.
In the book, the Fellowship knew that Saruman was in league with Sauron by that time, and they would have to pass Saruman's tower at Isengard if they took that path. In the movie, the Fellowship is unable to cross the Misty Mountains because of Saruman. He is using his magic to cause havoc with the weather and causing avalanches, making the way impassable.
Yes he fantasised over her, the agreement with Saruman upon the fall of Rohan was that he would have her.
The prophecy said there would be four on the thrones. With only three, it was not complete and she would still have power.