Cassius: Jealous of Caesar and does not like him in any way fashion or form. He believes Caesar is not worthy of praise and is confused as to why an ordinary man like him can be lifted up and valued so greatly. He is manipulative, he is not honorable, he is strong-minded.
Brutus: Although he is swayed by Cassius's opinion and the people actions, he does have love for Caesar. He values his country over anthing. He is smart, conflicted, pensive and cautious.
The plural of studio is studios
They all have to do with the military.
The narrator is Strickland, as to his role: well it is his story.