Starting today, Cloud Drive will be used for file storage and Cloud Player will be used for music storage and playback - each service will offer separate subscriptions.
It turns out that you can dump the image files (JPG only) anywhere in the file structure of the player and view them using the Browser, but if you want to take advantage of the built-in slideshow-type navigation features (which aren't that great, anyway) you have to put the files into a specific spot.