You should not expect a tutor to answer all the parts of this question; you need to work on the problem yourself!
I will start you off.
The graph is a parabola opening downward.
The area involved is not all above the x axis...if you do a straight integration, you will get an algebraic area....and, in fact, I would ask what is really wanted before attempting to answer this part of the question or part B.
Part D is just [f(4)-f(-1)]/5
For the last part you need to find where on the interval the derivative of f(x) equals the answer in part D.