For 2, you are looking for maximums and minimums. You know that wherever these occur, they must be either higher or lower than the areas around them, thus they must look like a hill or valley. Since the top of a hill, and the bottom of a valley are flat, you are looking for places where your slope is equal to zero.
So find the derivative (because this gives the formula to find the slope), and set it equal to zero (because this will tell you where the slope is zero, meaning where the slope is "flat" or where it does not change, or where it is horizontal). Find the values for x which return this, then test the areas around it to determine whether it is a "hill" or "valley" (meaning maximum or minimum") then test the two endpoints (because they could be higher or lower, even though they may not be a hill or valley. and the highest of these values will be the maximum, and the lowest will be the minimum.