With Argument Part questions, you are essentially just slapping a label on a specific part of an argument (context, premises, conclusions etc.) Method of Reasoning questions require more “attention” because you must understand HOW an argument is being made. Hope that helps!

Not necessarily because, remember, some is a range (from 1-100) and could, in fact, include all.

Well, for both NA and MBT you are correct that both answer choices must be true; however, the key difference is why they must be true and how the answer choice functions. With a MBT you are essentially looking for a conclusion that must be true based on the premises that are provided in the stimulus thus creating a valid argument. With NA questions the stimulus already contains an argument (possibly a valid one) and you are tasked with finding an answer choice that must be true but also protects the existing argument.