The key inputs of creating user stories are Scrum Core Team, Prioritized Product Backlog, Done Criteria, and Personas. The most import tool is User Story Writing Expertise. And the major outputs are User Stories and User Story Acceptance Criteria.
Reference: http://blog.scrumstudy.com/how-are-user-stories-created-in-a-scrum-project/

Reference:
http://blog.scrumstudy.com/advantages-of-using-scrum-listed-down-by-scrumstudy/

The more uncertainty exists in a project, the riskier the project is. Therefore, it is important that riskier products in the Prioritized Product Backlog are given higher priority. Products carrying a higher level of risk will also require risk mitigation actions. When these risk mitigation actions are prioritized against the backlog, the result is a Risk Adjusted Product Backlog. Dealing with risks early in the project does not guarantee that the project will be successful, but it does enhance the team's ability to deal with risk.
Reference:
http://blog.scrumstudy.com/prioritized-product-backlog-the-backbone-of-a-scrum-project/

Explanation
The deployment mechanisms of each organization tend to be different based onindustry, target users, and positioning. Depending on the product being delivered, deployment can take place remotely or may involve the physical shipping or transition of an item.