You are evaluating the prospect of establishing a new facility. The initial setup of the facility requires a substantial investment of $50 million. It is projected to generate annual returns of $10 million indefinitely. Assess the Net Present Value (NPV) of this investment at a cost of capital of 5%. 

a. Determine whether proceeding with the investment is advisable. 

b. Calculate the Internal Rate of Return (IRR) and identify the maximum acceptable variance in the cost of capital estimate that would not alter the decision