In "You had that same look in your eyes," it means the person’s expression or the way they looked is familiar, possibly from a past experience or "another life." It's about recognizing something familiar in their eyes.
"Don't act so surprised" is a casual way of saying, "Don't be surprised," meaning they shouldn't show shock or disbelief about what’s being said. It’s not exactly literal, but more about telling the person not to react with surprise.