The service manual is nowhere to be found and the info you are looking for is only found in a few service manuals for older printers. Most available service manuals do not have this info. Canon's website does not give detailed info in the specs about this and I guess it is not found in the user manual either?
The pigment black cartridge is only used when plain paper is selected, when photo paper is selected only the dye inks BK, C, M, Y, GY are used. I don't know more about the ink usage than that.