I do not agree with the answer provided for part a of question 5.  Or may be I do not understand the question.  I think both students are correct exactly half of the time.  Whenever the block is headed toward equilibrium the spring force is in the same direction as evidenced in the fact that the velocity is increasing on the way toward equilibrium.  Student A's statement is correct for that time frame.  Student B's statement is correct when the object is headed away from the equilibrium point.

Jacob, exactly right and thank you. I added Student C with the right answer. Clearly students A and B confused the direction of the force with the direction of the motion - rookie physics mistake.  John

The answer to Question #3 part c is VERY wrong.  The greatest tension is achieved AT the equilibrium point.  The reason being that tension at the equilibrium point is mg + mv^2/r and v is a maximum at the equilibrium point.  At the amplitude points, the acceleration is purely tangential (velocity is zero, so centripetal acceleration is 0).  Rotating the axis like with inclines, the tension force then becomes equal to mg (cos theta) where theta is the angle with the vertical.