I think she will have twins (a boy and a girl). No idea about the names.
One godfather/godmother per child is the Catholic norm.
The (future) head of the House Orange-Nassau as a godparent for the future head of the House Nassau. So King Willem-Alexander or Princess Catharina-Amalia are safe bets for godparenting if looking outside the family.
But the Nassaus do it calmly, like more Catholic families: the current hereditary Grand-Duke only has his uncle and namesake prince Guillaume as parrain and his aunt princess Marie Astrid as marraine.
One godfather/godmother per child is the Catholic norm.