If you use the equity beta and the security market line to compute the discount rate for a project, what assumptions are you implicitly making? What are the advantages of using the SML approach to...

If you use the equity beta and the security market line to compute the discount rate for a project, what assumptions are you implicitly making? What are the advantages of using the SML approach to finding the cost of equity capital? What are the disadvantages? What are the specific pieces of information needed to use this method? Are all of these variables observable, or do they need to be estimated? What are some of the ways in which you could get these estimates?