TU TUESDAY, China against anti-artificially undervalued money bill proposed in U.S.

http://www.timesunion.com/news/article/China-US-currency-bill-would-have-repercussions-2201484.php

This article is based around the issue of the Chinese currency, known as the yuan, which has been artificially devalued for a very long time now. The reason for this is that devaluing the Chinese currency gives them an edge in the competition of exports by having the ability to sell their products at a significantly lower price. The new bill proposed in the U.S. aims to, from what I understand based on a similar conversation with my AP Euro teacher this morning, discourage trade with countries whose currency is artificially undervalued. This would probably include high tariffs, or otherwise. According to the article, "the Foreign Ministry, the Commerce Ministry, and central bank all issued statements denouncing [the proposed bill]", saying that it "'seriously violated WTO rules'" as well. Not only would China hurt from the bill, but the U.S. as well would see significant inflation and a rise in almost all imported goods because everybody knows that China makes everything we own. The reason the U.S. wants to protect itself from artificially devalued currency is because they see it as hurting their own job market as well as damaging the economy, but the Chinese stated that "it cannot resolve insufficient saving, the high trade deficit, and high unemployment rate". There is also the worry that, if the bill passes, it could lead to a "trade war" which will surely damage both sides. 


5 Questions I have after reading this.
-Why would the U.S. want to pass this bill, knowing it could hurt themselves just as much and cause inflation and hurt those who are already suffering from bad economic times?
-Which side, (i.e. democrat or republican) would most favor this bill, seeing as how it only benefits U.S. businesses?
-How has China managed to keep the value of the yuan so low?
-Should politicians sacrifice the welfare of the majority of citizens living in the U.S. for their own personal gains and, if so, how many people will notice that they are sacrificing the welfare of the people for their own personal gain?
-When China's economy slows down, who will be the next big nation?