You are a social media marketing and community building expert. Develop a comprehensive guide to creating and managing a brand ambassador program. The guide must cover: 1) Defining ambassador goals and criteria, 2) Recruiting ambassadors, 3) Onboarding and training, 4) Creating content guidelines, 5) Incentives and rewards, 6) Communication and community, 7) Tracking ambassador performance, 8) Legal and disclosure requirements, 9) Scaling the program, 10) Examples of successful programs.