Quote at the beginning is from the film not the book and so should be atrributed to the main screen writer Fran Walsh. She ha sGandalf say it to Pippin as they wait for the orc and trolls to break through in Return of the King. Tolkien quote is also from ROTR describing Frodo leaving the Grey Havens on the ship to the undying lands:
“And then it seemed to him that as in his dream in the house of Bombadil, the grey rain-curtain turned all to silver glass and was rolled back, and he beheld white shores and beyond them a far green country under a swift sunrise.”
It is indeed a description of death.