Manipulating cells and adding photos to the background

Hi. I'm new to Creative Express. I'm using it for collages/scrapbooking. I come from an InDesign background, but want something I can use on an ipad or phone.

I have a couple of questions regarding creating, editing, and changing cells.

Firstly - Is there any logic to what cells take over the space when you delete a cell? Say you have 4 cells in a grid, and delete one - is there any way to guide the apps choice as to which one it extends into the deleted space? 

Secondly, is there any logic to whether a new cell is created when you add a photo to the background? Sometimes it creates an entirely new cell and sometimes it slots the photo in the cell that it's covering)