I'm trying to understand what I'm seeing on the forum.
If I buy PS Touch, it believe that it can read any photo on my device. On external USB drives as well?
So then I can edit the picture and save it... either as a JPG/PNG locally or in the "Creative Cloud"
Does that then suggest that some form of membership of Creative Cloud is included in the price of PS Touch? Is this some kind of permanent membership?
You can sign up for a Creative Cloud membership for free; at the basic level, you get 20 GB of cloud storage.
You have many options of saving a PS Touch project. (Your PS Touch projects stay as just PS Touch projects; anything you import into a PS Touch project stays intact and separate; anything you save is simply exported and separate.) e.g., You can save as a JPEG or PNG locally on your tablet; you can save to Creative Cloud as a PSDX; you can save your project as a plain-vanilla PSD file and email it to whomever. Remember to think a little differently here; it's not the same as opening an image in Photoshop and having to directly work with the original image.
You can also save to services such as Dropbox (in all four formats) if you'd like. (I know I can do this in the Android version; can't speak of the iOS version but I'm assuming it's the same.)