Is every image style I have for each image upload auto-created?
The styled images will be created on first request, creating a new file with the styled image. This will not only save space if you have tons of image styles but also CPU power - because if you attach 10 images to a node and want to create 12 (as you mention the number) different image styles, that will put quite a load to generate all the styled images in one go. Doing this when needed is far better management of resources.