This is nothing to do with page setup, layout, printing preferences or anything but Apple's inability to handle print drivers properly.
You are suffering the 1/4 page syndrome, if you lok elsewhere in this forum, on the Guttenburg site, and other non-tied Apple sites you will find pages on this problem.
Are you printing over a network, or directly through the USB port?
The Apple seems to be particularly stupid, so you can use the "Wrong" driver. Try "Adding" drivers from higher up the range, you may find one that works. In the printer list are Canon drivers and "GIMP" drivers.
My Canon iP3000 works fine plugged into the USB port using the Plug & Play driver, but printed 1/4 page over the network. I tried various drivers till I found that the GIMP version of the bjc8000 driver seems to work.
As far as Apple are concerned, you are on your own.