Please answer the question below, provide good explanation and examples to support the answer. Also provide references.

1. Explain the relationship between market price and a firm's profitability in a perfectly competitive market.
2. Explain how the zero-profit point and the shutdown point for a firm operating in a perfectly competitive market are each determined.
3. Explain whether a patent should be used to provide an incentive for investors? If your answer is positive, explain whether there should be any limits or conditions relating to the same.