How can I change the page number orientation? The chart is landscape, the
page number should be verticle when bound into a book?
Try producing the graph in portrait mode, not landscape, so that the
page number comes out right. Then rotate all the other elements of the
chart (axis labels etc.) by 90 degrees in the "Alignment" tab of the
formatting dialogue. This should get you back to a landscape chart
again.
It may not be possible to rotate the chart title like that. If so,
you'll have to use a text box for your title instead.