What happen with the images (image, image gallery) of one item when I delete this item?

The images and gallery of the item are only deleted when you remove the trashed item from the trash. When you just put it in the trash and don't delete it permanently the image and gallery are not deleted in case you want to restore the item.

That's amazing. Great job again ;)
On default Joomla articles system you have to delete the images separately from content article.