Change management is important in a project because it provides structured processes and management products to manage and implement changes effectively. This ensures that all changes are assessed, approved, managed, and documented properly, helping the project adapt to changes while maintaining control and alignment with project objectives. References: PRINCE2 Foundation official resources and training on change management.

In PRINCE2, a project benefit is defined as a measurable improvement that results from an outcome perceived as an advantage by one or more stakeholders. Benefits are the positive effects or gains yielded by the project, which contribute directly to the organization's objectives. References: PRINCE2 7 Foundation Handbook and official training materials.

In the 'risk management' technique within PRINCE2, considering the organization's environment is essential during the 'Identify' step. This phase involves understanding the context in which the project operates, including external and internal factors that could affect the project. This context is crucial for identifying potential risks that could impact the project's objectives.References: PRINCE2 7 Foundation resources on risk management technique.

When defining the number of management stages in a PRINCE2 project, it is essential to consider when key decisions need to be made by the project board. Stages are often structured around the need for key decision points, enabling the project board to review progress and make informed decisions about whether and how the project should continue. References: PRINCE2 Foundation Handbook, Tailoring PRINCE2 - Stages section.

The Initiation Stage Plan specifies how the project board should approve management products produced during the 'initiating a project' process. It sets out the plan for the initiation stage, detailing the management and control of this stage, including how deliverables are to be reviewed and approved.References:
PRINCE2 7 Foundation Source: PRINCE2 Foundation handbook and online resources