child theme

Hi there, as suggested to me in a separate post, I have created a child theme, so that I can change the css. My child theme (well the css for it) resides in a folder called twentyeleven-child, a child folder of themes. Now, I need to insert some images on my site https://andys.antonioborrillo.co.uk/wp/?page_id=12 and I wonder if it is better to add them into the images folder within the twentyeleven folder or I should create another images folder in my twentyeleven-child folder.

Generally speaking, should the folder structure in my twentyeleven-child folder reflect the folder structure in the original twentyeleven folder or it really doesn’t matter? I give you an example. I have created another version of the header.php file which is now in the twentyeleven-child folder, but if I look at the original theme folder, the header.php resides in a header folder if that makes sense.

What I really wonder is, if I put my own images in the original theme folder, is there any risk that they get deleted at all?
thanks