How to close the gap between non-Econ background and Macroeconomics
Sorry if this sounds harsh, but: 

You need to start asking more. You're not stupid for asking questions - you're stupid for not asking questions. Be upfront about your different background and ask away. 

Of course you should try to research things by yourself, but a lot of assumptions are next to impossible to know or find out in a reasonable amount of time. I've got a 5 years of university economics - primarily in macro and I still struggle with assumptions. So, if you can't find it - ask! And ask your professor about some relevant books / articles.