i dont think id go so far as to say that her death broke the first triumvirate and caused the civil war...there were too many other factors involved to say that. certainly, though, her death severed an important connection between pompey and caesar, which made it easier for them to go to war against each other.
geez, have they ever asked a question on women? i dont thinki know enough about them to write an essay. ok, lets see..
octavia: obviously, key figure in political manouevres of the 2nd triumvirate. used by Octavian to further his own political ambitions - not just in creatng bonds between triumvirs by marrying antony but how he used her marriage breakup with antony in his own political propaganda.
Fulvia: know she was very vocal against Cicero and was one of the people who insisted that he be proscribed when the 2nd triumvirate was formed (although, antony would have done it anyway as revenge for the philippics, so this may be a moot point). people often say that, after Cicero's death, when his head and hands were nailed to the speakers podium that Fulvia drove golden hairpins through his tongue in revenge for what his speeches had done to Antony, but sources are conflicting on whether this is true or not.
Servilia: gadzooks, i dont know anything about servilia...except...except. nah, i got nothing. i dont think she really played all that big a part in the grand scheme of things. could (and most likely are) be wrong though.
hope that helped at all.