Is Part A as simple as accepting the individual projects with an expected return greater than 15%?

For Part B, would you use the Expected Stock Return formula and accept projects greater than 15%? For example, project #1, r = 8 + 0.5(7) = 11.5%, so do not accept this project? For project #2, 8+0.8(7) = 13.6, don't accept?

I thought we were supposed to use rf + B(rm-rf)?  It looks like you are just using rf + B(rm)? 

Also for part A on Excercise 8.2 where does the yeild to maturity come in?  Maybe I am reading the problem wrong, but don't I use the annuity formula on page 39:

C= 6million, r=0.08, and t=7??  Or of I just take the sum of (6million/1.08 + 6million/1.08^2, etc for the 7 years) and then use r=.10 in the annuity formula?