Answer to Question 1
The three methods are emission charges, cap-and-trade, and taxes. Emission charges set a price per unit of pollution that the firm pays to the government. With a cap-and-trade policy, the government issues marketable permits to firms that allow them to pollute by an amount assigned by the permit. The permits can be bought and sold among firms. Taxes can be imposed on polluting firms. If this tax equals the marginal external cost, efficiency can be attained.
Answer to Question 2
Manufactured goods enjoy more productivity gains most of the time over services. The reason is that machines can do more and more of the work with technological breakthroughs. However, gains in productivity in cutting hair and college education are harder to come by as the primary input in both is human and requires a relatively fixed mix of human and capital inputs in the production process.