How do I copy or delete a page?

The easiest way of doing this is by going to View > Show Page Thumbnails and then to click on a page and select Edit > Cut, Copy or Delete and then Edit > Paste.

But note that what you copy is not a "page" but a "section". A section can contain several pages. To split a section into several pages you go to Insert > Section Break.

If you want to copy just the objects (graphics, text boxes...) from one page to another, the easiest way is to highlight them all.
1. Shift-click object after object, until you have them all.
2. Go to another page.
3. Make sure that your cursor is not in the body text (you do this by clicking in the margin of the page).
4. Select Edit > Paste.