Via Creative Clouse, I imported several PSD files on my iPad3 who consist of several layers. However, independ which file I import these PSD files open without layers. That is, they open displaying the layers who were enabled (visible) when they were saved in Photoshop.
Does this means I only can create layers in Touch, but not work with already existing layers from non-Touch PSD files?
Correct. (Kinda sorta.) You can export PS Touch projects as PSD and PSDX files into Photoshop CC/CS6 and have their layers preserved, but if you import a PSD file into PS Touch, the layers will be flattened. I imagine this was done as a failsafe mechanism. (PS Touch works with 12 layers max, versus the thousands of layers available in Photoshop CC/CS6.)
Oddly, once you open a PSDX file in Photoshop CC/CS6, you cannot save it as a PSDX; you're forced into saving as another compatible format like PSD. (I'm thinking this was another failsafe mechanism since PS Touch does not support features such as adjustment layers.)
PSDX files can be uploaded and downloaded from Creative Cloud to PS Touch and have their layers preserved.