In the 3D book video I concentrated of creating the book and pages. To get the images onto the pages, I suggested that an image editor was used. That way you get to arrange the images on each page. So, you would open page 1 of your book into an image editor like Photoshop and add the images there. Then save that page with the same name, back into your project folder. It replaces the original page, but now it has your photo content on the page.
Alternatively, create your images (you would still need an image editor) at the same size as the pages and save them with the same name as the page, so the image becomes the page. This is not quite so creative as using an image editor.
The fact that you need both portrait and landscape images on the pages, suggests you should be using an image editor. Do you have one and can you tell me what that is. Photoshop, Elements ?