Like a star of heaven
In the broad daylight.”

2. Metaphor:

“From rainbow clouds there flow not
Drops so bright to see,
As from thy presence showers a rain of melody.”

“Or how could thy notes flow in such a crystal stream!”

“In the golden lightning
Of the sunken sun.”

3 and 4. Metonymy and Synecdoche are nearly related and in this poem the examples are numerous. Here are a few:

“Better than all treasures
That in books are found.”

“Teach me half the gladness
That thy brain must know.”

“Thou art unseen, but yet I hear thy shrill delight.”