A developer who has almost completed a required product feature for a prototype leaves the company in the middle of an iteration. What should the project manager do?

A project is nearing completion. The sponsor is already asking the project management office (PMO) when the project manager will be assigned to host a planning session for a new initiative.
What should the project manager do next?

During the execution of a project to develop a prototype, the customer asks the project manager to stop the prototype line and purge a specific component based on recent reliability tests that have deemed the component to be deficient. The project manager checked the quality management plan and there is no reference to this component.
What should the project manager do next?

During the first project meeting with a new project manager, a stakeholder complains about not receiving periodic reports. What should the project manager do first?

The project manager has finished all the tasks of the project and immediately starts on a new project. A few months after beginning the new project, the accounting manager asks for confirmation of previous projects because the budget is still open with no further cash flows.
What should the project manager have done?