This is just to make small discovery public (I didn’t find this anywhere else). When creating books in iPhoto, you can fine tune and edit layouts by using combinations of modifier and arrow keys!
This is great news, you see, because I always used to use trial versions of Aperture to be able to customise the layout — and granted, you are much more flexible this way. But, while there are no more trial versions of Aperture, this now be be done (to some extend) in iPhoto:
First: Select the box you want to edit (it will be highlighted in blue).
Then: Press command + arrow keys to move the object around. Command + option + arrow keys will resize the box. If you add in the shift key, the step size will be much larger.
Here’s a video demonstration: