RE: Basic questions on behalf of a newbie
The book you are currently reading will show at the top of each Collection (I assume your wife has set up Collections to categorise the different genres) or she can Show By Most Recent First on the Home Page. The book will open on the last page read.
Some books - but not all - now have page numbers, but you can only view them briefly. Usually the ones that are not indie published have page numbers. With the book in question open, click on the Menu and the page number will be displayed at the bottom of the page. Other than that, of course, you will see the percentage read at the bottom of the page.
As for short stories, why not have a Collection called Short Stories. But if you really want to know exactly how many pages, you would need to have a quick look at the Amazon page. So, with the book closed, but underlined by the cursor, click Menu/Book Description and that will take you to the book's Amazon page.
A book is like a garden carried in the pocket. ~Chinese Proverb