1- GDP is a good form of measuring our economic well-being. The reason for this is because GDP is the total market value of all the final goods and services produced within the economy in the year.
2- The trade deficit reduces our GDP because the excess of imports over exports makes the total number of market value of final goods and services made in a year.
I think that between both the most important one is nominal GDP because it is the value of GDP in current dollars.
4- The difference between GNP and GDP and what they produce is that GDP is what their citizens earn while GNP is the gross national product. This GNP is usually not to important to most countries.
5- The reason investment spending is more volatile than consumer spending is because investment spending is more likely to change rapidly and it is also unpredictable. While consumer spending is less liable to change and tends to be more predictable.
6- A consumer confidence is closely watched because if the way a consumer thinks about a business is important. Consumer confidence lets people to still have hope even when in deep in a financial crisis people will still remain to believe on that the economy will get better.
O'Sullivan, Sheffrin, and Perez. Macroeconomics Principles,applications, and Tools. 8th ed. p.97-114.: Pearson, 2014,2012,2010. Print.