If I click on next page when I am on the last page, I am taken to a blank page rather than it cycling me back to the first page. Sometimes I find that one of the input boxes is shown. Why is this?

Sometimes if you start off with a number of pages & then reduce the number of pages, it is easy to forget to delete or move all the objects to another page. If you then change the size of the operator interface screen the objects can end up on a part of the screen which is not displayed. Temporarily increasing the screen size will soon reveal any objects which have been left behind. Deleting them will then solve the problem.