The Question and Answer section for In the Time of the Butterflies is a great resource to ask questions, find answers, and discuss the novel.
Minerva is a symbol of the revolution. She refuses to be oppressed in her country and her life.
This depends on what point in the novel you are referring to. Dede really only finds her voice against the government after the death of her sisters.
Margarita delivers the letter, which is for Patria from her sister, Maria Theresa.