To "catch someone's eye," is an idiom. Idioms are phrases that have literal and figurative interpretations. You could, theoretically, catch someone's eye, however, the phrase is commonly used in its figurative understanding, to get someone's attention.
Glowing with pride is an example of imagery. It is visual imagery to be specific. Imagery helps us use our senses to understand the picture a writer is trying to create. This example describes the warm, knowing satisfaction that someone might have while they were looking at something they or someone they love accomplished.
Asking a million questions is a hyperbole. Hyperbole is an exaggeration that is not feasibly possible. The author is simply trying to verbalize the feeling of having so many questions.
I hope you are enjoying The Giver.