Answer:
The unbalanced rhythm emphasizes the subject's lack of beauty. The stressed syllables highlight the speaker's dislike for the subject. The consistent rhythm softens the speaker's unkind words about the subject.
An allusion -- the writer is making a reference to another work or incident
Well, that sentence was a type of : Declarative sentence.
Declarative sentence is usually used to relay information or ideas. In this sentence you can see that it give some more detailed information about the painting.
hope this helps