They are both considered metaphors, yes. The light of my life means the happiest thing that you have ever known. It's kind of an exaggeration, but it's metaphor. Roller coaster of emotions means that your mood swings up and down and all around like a roller coaster. I hope this helps you!
What is that supposed to mean?
I'd say that the rescued words would be
save, save from danger, save the life of, come to the aid of;
free, set free, release,liberate
