Capital structure (beta, rate of return, risk premium, refinancing)

Having some trouble with the below practice questions, and would appreciate any help! I’ve included some workings for Q2, Q3, Q6, & Q7. Thank you!

Hello Sunshine Inc. is financed entirely by common stocks and has a beta of 1.0. Assume that the firm pays no taxes. The stock has a price-earning (PE) multiple of 10 and is priced to offer a 10% expected return. The company decides to repurchase half the common stocks and substitute an equal value of debt. Assume that the debt yields a risk-free of 5% and a beta of 0. Calculate the following:
Q1) The beta of the common stocks after refinancing
Q2) The required rate of return and risk premium on the common stocks before the refinancing
risk premium = risk free rate – expected return
risk premium = 5% – 10% = -5%
Q3) The required rate of return and risk premium on the common stocks after the refinancing
risk premium = risk free rate – expected return
Q4) The required return on the debt
Q5) The required return on the company (i.e., stock and debt combined) after the refinancing

The Duffers Brothers Inc. wants to set up a private cemetery business. According to the Chief Financial Officer, Shawn Levy, business is “looking bright”. As a result, the cemetery project will provide a net cash inflow of $180,000 for the firm during the first year, and the cash flows are projected to grow at a rate of 4% per year forever. The project requires initial outlays of $2.2 million.
Q6) If the company requires a return of 11% on such undertakings, should the cemetery business be started?
Pt = Dt + 1 / R – g
Pt = $180,000 / 0.11 – 0.04 = 2,571,428.571
NPV = PV of CF – Initial Investment
NPV = 2,571,428.571 – 2,200,000= 371,428.571
R = 371,428.571 – 180,000 / 180,000 = 106.349%

Q7) The company is somewhat unsure about the assumption of a growth rate of 4% in its cash flows. At what constant growth rate would the company break even if it still required a return of 11% of investment?
180,000 / (11% – growth rate) = 2,200,000
11% – growth rate = 8.181%
growth rate = 2.819%
The growth rate must be at least 2.819% for the firm to break even.