That is definitely a metaphor :)
There is no metaphor in this but it is more describing what her eyes are like. You are complimenting them because you are saying the world is beautiful when you look into her eyes
No, that is not a metaphor.
Metaphor
Blue can be used metaphorically to represent feelings of sadness or melancholy, as in "feeling blue," but it does not inherently function as a metaphor without context.
he/she is angry and there for their eyes show it!
This metaphor indicates that her eyes are bright and full of joy or happiness. It suggests that she is feeling excited or pleased about something.
It means she's special
metaphor
Yes
Her eyes were the sea.
His eyes were a tranquil green pool, flecked with brown and gold in the sunlight (metaphor) or Her eyes were hazel like emeralds burried in dirty (simile)