How do you know whether a User Story is well written or not?

During which milestones do you write or revisit epics?

How do you sync functional specs with design across multiple platforms?

What is the best way to keep track of software requirements with minimal effort?

How detailed should your requirements be?

Do you group features by whether it is a base feature vs. a special-add on?

What's the best method for tracking and reporting on requirements and dependencies across scrum teams in other business units?

What process do you use to prioritize product features required from multiple stakeholders?

When you are developing mobile apps, do you write separate stories for UX and Dev (in your product backlog)?

What is the best way to document Business Logic and how do you keep track of the changes?