Answer to Question 1
When market demand decreases, the market price of the good falls and the market quantity decreases. Because the price equals marginal revenue, the fall in the price means marginal revenue falls. As a result, each firm moves down its marginal cost curve so each firm decreases the quantity it produces. The firm's economic profit falls (or its economic loss increases). If the firm had been making a normal profit before the decrease in demand, after the decrease the firm incurs an economic loss.
Answer to Question 2
A