The software that comes with the camera is "powered by" Silkypix. The actual Silkypix Developer Studio software is a completely different product :you can find the details here
Official SILKYPIX page: the best RAW converter for digital images Well worth the purchase, I dont even have the Pentax software installed.
To answer your question however you can use the Pentax software to process raw images and then do further adjustments in another program like PSE. When you save the raw image you should save it as a TIFF file with no resizing. Then you can open that in PSE and edit it.
Adobe Camera Raw is also a raw converter. You would process the raw file in either the Pentax software or ACR, but not both. Once you have run a raw file through a converter you save the image as another type of file, jpeg,TIFF etc. The raw file remains untouched.