During which process of Project Cost Management does a project manager produce the cost baseline?

At which point of the project is the uncertainty the highest and the risk of failing the greatest?

A contractor has provided hands-on training to a team member on new equipment that has been purchased as part of the project. The team member has acquired key insight and experience on the new equipment.
What is this an example of?

When project requirements are documented in user stones then prioritized and refined just prior to construction, which approach is being used for scheduling?

The focus on continuous communication with all stakeholders, including team members, is part of this knowledge area: