I know nothing about rhetorical devices

explain what types of rhetorical devices are being used or why the speakers chose to use the words in that particular way.
Use other examples from the texts to support your assertions if necessary.

Five score years ago, a great American, in whose symbolic shadow we stand today, signed the Emancipation Proclamation. (Hint: Think about where the speech is being delivered and what other speech began with a phrase similar to that. Why might King have chosen those words?)

This momentous decree came as a great beacon light of hope to millions of Negro slaves, who had been seared in the flames of withering injustice. It came as a joyous daybreak to end the long night of their captivity. (Hint: Think about figurative language.)

Why did King repeat the words “I Have a Dream”? (Hint: In the complete text of the speech, the phrase is repeated several times.)
“...when we allow freedom to ring, when we let it ring from every village and every hamlet, from every state and every city, we will be able to speed up that day when all of God's children, black men and white men, Jews and Gentiles, Protestants and Catholics, will be able to join hands and sing in the words of the old Negro spiritual: ‘Free at last, free at last. Thank God Almighty, we are free at last.’” (Hint: Remember that these are the last lines of the speech. What effect do you think they had on the audience?)

What we need in the United States is not division; what we need in the United States is not hatred; what we need in the United States is not violence and lawlessness, but is love and wisdom, and compassion toward one another, and a feeling of justice toward those who still suffer within our country...

We can do well in this country. We will have difficult times. We've had difficult times in the past. And we will have difficult times in the future. It is not the end of violence; it is not the end of lawlessness; and it's not the end of disorder.

But the vast majority of white people and the vast majority of black people in this country want to live together, want to improve the quality of our life, and want justice for all human beings that abide in our land.