Thanks for the questions! Just fyi, in order to keep things separated and thus as clear as possible for students searching for specific answers, I split your four questions into four separate posts. I hope that is ok with you
With #4, it's completely understandable as to why you thought that this question might be a Main Point question. But, it's possible for a conclusion to be drawn from a set of statements and for that conclusion to not
be the main point of the argument. A typical set of statements allows for several different conclusions to be drawn; some of those will be simple inferences, and so it's possible that the correct answer to this type of question is just one of those types of conclusions.
Further confusing the issue is that the answer here could be the Main Point of the argument. It's just doesn't have to be the Main Point, and it could be something more minor. This is how the test makers use language to keep you slightly off-guard and to allow for a greater range of possible answers.
If they wanted you to know for sure that you were looking for the Main Point here, they would have added some additional information (such as, "...which one of the following is the main conclusion..." or "...which one of the following is the primary conclusion...").
Please let me know if that helps. Thanks!