I believe that the big questions in life you are asking about are,

"Have you found someone to share your heart with?

Are you giving to your community?

Are you at peace with yourself?

Are you trying to be as human as you can be?" ("The Classroom")

Morrie directs these questions to Mitch on the first meeting of their "class".  They will be the questions upon which all the other discussions to be held would be based.  Morrie presents the questions at the outset of the meeting with virtually no preamble.  Knowing that he has so little time, he gets right to the point. 

Morrie's questions make Mitch squirm, because he wants "to show that (he) (has) been grappling deeply with such questions".  The questions, according to Morrie, are the secret to living happily, and Mitch, upon reflection, knows that he is not satisfied with his life.  He remembers the ideals that he once had, and wonders, "What happened to me?", and he realizes that even though his days are full, he remains "much of the time, unsatisfied".  Morrie's purpose in asking the questions is to help Mitch discover why, like so many others in the world, his life is not fulfilling.

Morrie knows that incorrect answers to the four questions he has presented are the basis for much of the unhappiness in the world.  He makes his point by sagely commenting that "dying...is only one thing to be sad over...living unhappily is something else...so many of the people who come to visit me are unhappy" ("The Classroom").