The author is primarily concerned with? Is this a primary purpose question or the main idea question?

GRE Verbal Problem Solving
1

The author is primarily concerned with? Is this a primary purpose question or the main idea question?

2

This is asking why did the author did something in the passage while the main idea tends to go towards what did the author mean while writing this.

3

Primary purpose and main idea cannot be the same?

Also, conclusion will be the main idea?