What is the plot of Act 3, scene 1? I know the climax are the two deaths, but is the rising action the fight?
Yes, rising action will be anything that occurs before the climax of the play. Shakespeare had a very specific plot diagram for his tragedies: exposition, exciting force, rising action, climax, falling action, catastrophe, and then resolution. The death of Tybalt is the climax - the point of no return / greatest tension - the events leading up to his death can be considered rising action.