Did john f. kennedy`s delivery of the speech affect the message he delivered?

Yes, because the way he delivered the speech moved the audience. The audience is captured by the way John F. Kennedy moves and speaks. The way he speaks is specifically directed towards the audience and America in general.

A Duty is a responsibility that can exist because of moral or legal obligations. You're required to do those. A citizen's responsibility is something that is expected from you to do in order to help improving the society, but it is not mandatory. Voting and defending the constitution are a citizen's responsibility, but not voting and arguing against the constitution are also a citizen's rights.