During the development of a product, multiple identified risks have now become issues, which is hindering the team's velocity. What should the project manager do in this situation?

What is the correct way to put an organization on the proper path to changing their mindset to an agile approach?

A project manager has experience working with a specific provider that has been requested for an upcoming project. This provider often fails to meet deliverable dates; however, it is the only company with the specific experience required for the project.
What should the project manager do during the planning phase?

A project manager is assigned to a new water treatment plant project that has been delayed for many years. It is revealed in the project charter that the sponsors of this project are from three different business units. This is the first time the sponsors have ever implemented such a project.
What should the project manager do?

A project manager assigned to an engineering construction project is receiving questions from the site engineers. Several questions are related to carrying out activities to meet timelines that compromise the work crew's safety. When reviewing these questions, the project manager realizes that the engineers do not (eel empowered to make decisions.
How should the project manager address this?