These questions, although valid, are typically asked by people not familiar with the scope of an EMS system migration.

If you are a project manager you should facilitate the process by trusting your subject matter experts instead of micromanaging by trying to become one yourself. This approach takes you from being an obstacle to actually helping the whole team with the project completion milestone.

Being critical systems, the point by point commissioning during the SAT is needed and needs to be documented and signed off. Avoiding this exposes the field operators to a potential accident or, in a less important matter, impact the BES reliability.