For the first question, what do you propose for the integrand in cylindrical coordinates? Do you know the geometry of the function in the integrand? If the geometry is elusive, use the cylindrical-Cartesian coordinate relations themselves. What are r, and z in terms of x, y and z? If you are new to changing coordinates, these are the first equations you should write down. It may help to note that cylindrical coordinates are just polar coordinates with the z-axis added.