hi, to make your image the right size in maya, open the jpeg in paint and goto image/atributes make a note of the width and hight, then in maya make a plane and make the grid width and height the same, then you can scale it down using the scale manipulator tool. for your next question im not sure what you mean, either you wana view one port on your screen (press spacebar on the desired viewport) or yo want to scale your image down more so that the grid is bigger