Response to Question #1:
Othello’s reaction in line 35 suggests that Iago’s accusations regarding Desdemona are finally beginning to affect him. Just before, Othello is interrogating Iago with clipped lines like, “What hath he said?” and “With her?” In line 35, Othello begins talking to himself, rather than interrogating Iago. He also begins to use the same type of flawed logic that Iago has been using all along to convince him of Desdemona’s alleged betrayal. In line 40, Othello says, “Nature would not invest herself in such shadowing passion without some instruction.” He is basically saying, “I have doubt, so it must be true.” Rather than trying to prove Desdemona innocent by demanding specifics from Iago, Othello has determined her guilt with no evidence except his own feelings. At that point, it is easy for Iago to show him “evidence” by tricking Othello into thinking that Cassio is discussing Desdemona, when in fact, he is talking about Bianca. By this point, Othello is primed to believe Iago, and so seeing Bianca with Desdemona’s handkerchief is all the proof he needs.
Response to #3
Aristotle defines catharsis as a purging of pity and fear. Experiencing catharsis at the hands of a playwright such as Shakespeare does not necessarily mean we are no better than Iago. In many plays, catharsis comes as a result of seeing justice done. Even though Desdemona was an innocent, she was a necessary casualty of justice. That does not mean we do not feel pity for her. It does not mean we don’t wish Othello would have come to his senses and maybe agreed to some marriage counseling. We feel remorse. Iago felt no remorse, no pity. Experiencing catharsis does not make us all Iago’s; it makes us better, because we feel that sense of justice and humanity.