If you are focusing on revenge you should center on the character of Iago, as it is revenge that drives his actions throughout the entire play. Iago seeks revenge for a number of both real and imagined slights. He wants revenge because he (falsely) believes Othello has cuckholded him with Emilia. He wants revenge because he feels that Othello has done him an injustice by choosing Cassio for the position of lieutenant. He wants revenge because he feels he has been overlooked for most of his life. What makes his thirst for revenge most scary is the fact that it is unquenchable. There is a distinct feeling that even the deaths of Desdemona, his wife, Othello, and Roderigo are not enough to full satisfy him.
Jealousy is a little more complex. Iago is jealous (for the reasons I cited above) and warns Othello of jealousy in Act III, Scene III when he says "O, beware my lord of jealousy! It is the green-eyed monster..." Othello's jealousy is quick, fierce and deadly. He is overwhelmed by his jealousy, losing sight of his love for Desdemona and his joy in his new marriage. He allows that jealousy to cloud logic and common sense. Bianca is jealous of Cassio and the owner of the handkerchief. Emilia has a moment in Act III, Scene IV where she says
But jealous souls will not be answered so; They are not ever jealous for the cause, but jealous for they are jealous. 'Tis a monster begot upon itself, born on itself.