You can upload any website-friendly image file type (.png, .jpg, .gif, etc.)

And yes, images with white or transparent backgrounds work well, too.

One consideration is the file size of your image. Crop or scale the image to your desired dimensions before uploading to Unbounce to avoid loading HUGE images that slow your pages down (that’s bad for users and bad for search engines).

Hey William, you can certainly edit the images with external software and separate out the layers.  If you import each separately, Unbounce should handle them fine as transparent PNG files.  Then you can arrange them as you want to appear on desktop vs. mobile or A/B if that’s your aim.  Unbounce does give you the ability to send images back or pull them to the front so that you can the image hierarchy.