This album is a clinic in vocal harmonies. In an interview with Kiske, he said that Dennis Ward was basically in charge of the vocals. Instead of the guys hammering out which parts they'd sing, Ward created a roadmap of who'd sing what. They said that 60% of the vocals were as planned by Ward, but that the other 40% were decided in studio after hearing each singer sing.
Kiske also said the Kai expected to sing Skyfall, and was pretty adamant about it.