Understanding IMF statistics I teach Politics and I've been asked to prepare a course which includes a lot of financial data because it covers recent international financial crises.
I've been trying to use IMF statistics, but I find them rather confusing. For instance, if I want to know a country's deficit, I find three different options:

And when I look up GDP, I have a bewildering number of options to choose from (I've highlighted the one that makes more sense to me):

Is there any rule-of-thumb method for a lay person to use these statistics? Alternatively, is there any other source in which the data is comprehensive but simplified?
Thank you so much in advance!
This is a general problem with anyone who comes face to face with official statistics for the first time.
Official statistics of a particular country comes from an institution of that country. However, there is something called the System of National Accounts that contains guidelines on pretty much every aspect of national accounts data. This is maintained by UN, IMF and World Bank, among others. Thanks to this you will find data definitions and compilation methods across countries to be largely consistent.
Rule 1: So if you have to use cross country data make sure that you select comparable datasets, i.e. choosing same variables.
Rule 2: Unless you are doing a deep data data analysis, it is okay to chose the variable which is seems most common. What is most common? The variable that you see easily available for any country.
Rule 3: Just keep in mind the difference between real and nominal variables. In most scenarios, you'd need real variables, especially, if you are doing cross-country comparison.
If you still get confused about what to use, the best way is to just read about the variable on wiki and you'll get some sense. Going into more details than what is easily available on wiki is only going to confuse you further as official statistics get fairly complex as you start peeling the layers.
Finally I'd recommend to give CEIC database a try, if you have access to it (through your institution). It is one of the best place today to find any data related to official statistics (I have seen even the officials from IMF using it).