Exposing to the right is usually good practice, but this is a bit too far I think.
As a matter of personal preference, 90% of the time I see a photo like this shot in landscape/horizontal orientation I find myself wishing it were shot in portrait/vertical.
As for the facial expression, I’ve taken countless baby photos over the last few years and I’ve found you can only succeed by a favorable combination of luck and brute force persistence (i.e., taking what feels like a million photos and hoping you get 2 or 3 really nice ones).