A PRINCE2 project should consist of a start-up stage, an initiation stage, and at least one other management stage to cover the remainder of the project. This structure ensures that the project is properly initiated and planned before entering into a series of management stages where the work is executed and completed, followed by a closing stage. References: PRINCE2 Foundation manual, PRINCE2 official resources

In PRINCE2, an 'internal' dependency refers to a relationship between two products of a project that is under the control of the project team. These dependencies are managed within the project's boundaries, unlike external dependencies which involve elements outside the project's direct control.References: PRINCE2 7 Foundation materials on product dependencies.

The purpose of the 'communication management approach' is to document how the project team will control and manage its interactions with stakeholders. This includes detailing the methods and frequency of communication to ensure all parties are appropriately informed and engaged throughout the project lifecycle.
References: PRINCE27 Foundation guide on communication management.

PRINCE2 requires a minimum of two management stages for any project: one to initiate the project and another to deliver the project. This structure ensures proper planning, delegation, monitoring, and control over the course of the project lifecycle.References: = PRINCE2 7 Foundation handbook and online resources

Acceptance criteria should indeed be agreed upon between the customer and the supplier. This ensures that there is a clear, shared understanding of the conditions under which project outputs will be accepted.
Acceptance criteria are detailed and measurable, contrary to being less specific than the customer's quality expectations. They can also be modified if necessary, provided there is agreement from relevant stakeholders.
References: PRINCE27 Foundation resources and materials.