How does the Cone of Uncertainty influence the work being done by a Scrum Team during a product’s development lifetime?

Scrum has no explicit artifacts for the product vision and a Sprint Goal. Yet, they are important. How would you explain their importance?

What practice can be used by the Scrum Team each Sprint to get Product Backlog items in the Product Backlog ready for selection during Sprint Planning?
Describe the practice and its outcomes.
What does “Ready” mean in the context of Scrum?

A Product Owner is confused about this sentence from the Scrum Guide: “The Product Owner is accountable for maximizing the value of the product resulting from the work of the Scrum Team.” He reaches out to you, the Scrum Master for clarification.
Educate the Product Owner by providing one specific example from your experience on the meaning of the previous sentence.

When working on one software product with multiple Scrum teams in Scrum Nexus, what is important about the dependencies of the planned Backlog Items and integration of the work being done?

A valuable and useful product Increment needs to represent the product’s non-functional requirements; such as, stability, security, financial integrity, performance, reliability, extensibility, marketability, and other requirements.
From your experience how have you captured these types of requirements?
How do you know that the Increment is compliant to the non-functional requirements?