Ex-Works has the lowest risk to the supplier- in Exworks the buyer collects the items directly from the supplier - so they have all the issues and risks of transporting it back home.
There are many question on Incoterms CIPS can ask. But as there's such a huge bank of questions it's really hit or miss if you'll get one of those question. Two students sitting the exam at the same time in the same study centre can get different question sets. One person can get 3 Incoterm questions and the other gets 0.
I would learn the major ones- the ones at the ends of the table in particular because these are the ones question are likely to be about. Ex works / Free carrier and Delivered at Place Unloaded/ De-livered Duty Paid in particular.
I like this graph as I'm a visual person. I think it makes it easier to understand than the study guide:
Shipping Incoterms: the Complete Guide - Guided Imports