I see flaw questions as the exact same as assumption questions. I ask myself "what do I need to assume to make this argument work." Then I look for the answer choice that basically says that assumption can't be made.
I have been working on flaw questions for a few days ... a start in tackling these flaw arguments. Also, should I be ... so much time on these flaw questions? I feel that flaws ... can spot them in the flaw questions it would possibly help ...
you MUST pre-phrase in weaken questions, this helped me immensely. By "pre-phrase" I mean, actively look for the weakness (where the author jumps from premises to conclusion), and find the flaw in that space.