Were you only given the PC update to fix a PC defect? That is done sometimes. With the patch kits you often don't have to update all components for a particular fix to get implemented.
There is both a PC download with the PC install, and a DA download that contains the DA, DR and DC (within the DA) installs same as a GA release.
The install for the upgrade is identical to a standard upgrade. The same process is followed as laid out in the docs to upgrade to these kits. This is because while we call these patch kits because they only contain defect fixes, they are in fact complete upgrade kits. They could be used to upgrade from prior releases, not just to upgrade the same release as the patch kit to install fixes.