Panchromatic , means that the film is color sensitive in relation to the Black, White, and Grey tonal range. Orthochromatic , is a special sensitivity to a color or colors.
Low contrast is when the image contains mostly gray values and few blacks or whites.
400 Speed film is a general purpose film used in average light conditions or out of doors. Higher ISO film speeds like 800 or greater are for low light light conditions found mainly indoors. Lower ISO film speeds like 200 or less are for use in bright sunlight or controlled studio lighting. The grain can be easily viewed with the help of a grain focusing device while the negative is being projected with the enlarger. Fine grain films will register higher contrast, higher resolution, and a lower speed.