Page number location

Create a separate Master page for each page size you are using. You can change the size of each Master Page (or Master Spread) as you set it up using the Page Tool. Then place a text frame at the bottom of each Master positioned from the bottom the same distance for all Masters. Each of these text frames should then have the automatic page numbering function active in it. To do this click inside a selected text frame with the text tool and then use Type Menu>Insert Special Characters>Markers>Current Page Number. Then when you apply your Masters to all of your document pages the page number will be in exactly the same spot relative to the bottom of each page.