The page dimensions (the one you setup in the printer option) could be dimensioned by dragging the border of the page preview directly in...
Could be great to have an automatic sorting in preview paer of multiple images in the print tab.
The border option is only inside the image dimension. Could be useful to choose between inside or outside.
The border in the printing tab is still in points. Could be useful to be able to change in cm or inch.
If you add many images and want to print with a plotter the rulers become tiny.