The "birdseye" symbol, called a fermata, means to hold the note until the director cuts you off. The squiggly line, a quarter rest, is a place in the music where you do not sing.
The repeat signs mark passages that should be repeated in music. This is used frequently in choral music. "Segno," called "the sign," is used to mark a passage to be repeated in a different way. (d.s. al fine means to go to the sign and sing to the end.) "Coda" is an independent passage written at the end of a work of music .