Accounting/Auditing

I have two questions that I need help with. 

Question one: What are the value and significance of COSO, SOX 404, SAS 112, and other pieces of legislation affecting the role of the accountant and auditor? Do these regulations protect the auditor or client more? If so, why

Question two: Explain the difference between evaluating, reporting, and testing internal controls for public and private companies. Under what circumstances might you attempt to apply the standards for public companies to private companies? When might you not attempt this? Explain your answers.