In my opinion it looks better to memorize the speech. But keep the paper with the speech written down with you just in case you forget something.
Either one is acceptable.
A part of speech -- there are eight -- defines the classification of a word. For example, run is a verb, house is a noun and so forth. A figure of speech is a phrase used for emphasis which is not...
Noun.
"speech" is a common noun A noun is a person, place, thing, or idea- "speech" is a thing