Old news (it was released a few hours ago), but for good order, the NY Fed GDP Nowcast estimate for Q1 comes in at 1.40% for the 1st quarter. That is unchanged from last week.  Below are the contributors and non-contributors given the releases this week. By the way, the Atlanta Fed estimate moved up to 2.3% on April 8th (from 2.1%).  Their next estimate will not be until Wednesday April 17.
So, yes, at any given trading center, it's an eight hour day. But that really doesn't matter, because somewhere in the world trading centers are open. You can trade anytime you want, although you should also note that you'll get the narrowest spreads -- the broker's profit margin -- when the maximum number of trading centers are open or, more precisely, when the trading volume for your currency trade is greatest. 

During the week the most active Forex trading days are: Tuesday, Wednesday and Thursday. Sundays (opening) and Mondays are days when traders are mostly watching and analyzing the market and predict further price moves. Fridays are traded approximately till noon, after that all actions slow down and almost freeze before the actual market closing at 5 pm EST.
The foreign exchange market is the "place" where currencies are traded. Currencies are important to most people around the world, whether they realize it or not, because currencies need to be exchanged in order to conduct foreign trade and business. If you are living in the U.S. and want to buy cheese from France, either you or the company that you buy the cheese from has to pay the French for the cheese in euros (EUR). This means that the U.S. importer would have to exchange the equivalent value of U.S. dollars (USD) into euros. The same goes for traveling. A French tourist in Egypt can't pay in euros to see the pyramids because it's not the locally accepted currency. As such, the tourist has to exchange the euros for the local currency, in this case the Egyptian pound, at the current exchange rate.