Thanks for posting! I’d be happy to answer your questions.
The short answer to all is yes
The longer answer is that many of our customers use a laptop as you describe in that they close the lid to disable the internal display and use the two additional displays afforded by the dock as the primary and secondary displays. If I had to guess that is the most common arrangement.
Adding the USB switch into the mix as you describe with your desktop PC should work in the same manner. Once you have the DisplayLink driver installed on the desktop system it should work fine ‘headless’ when connected to the dock via the USB switch.
Let us know if you have any additional questions!