Hello, Paul, sorry I did not see you respond to this thread sooner. On your first question, there are several kinds of conneciton methods. The Primary being (USB) and the other being on your Local Area Network (Wireless/ Ethernet). This message means that the printer can be either set up through the USB connection or through your network.
As for the issue with the port chioce, I would just designate one and then switch the cord between the available options until you find the correct USB that will be used.
In the %temp% folder you should delete all the folders, however some will be in use and they cannot be deleted. All others are used files that for all intents and purposes just take up space.
Let me know if this helps! I will be around to assist you in any way that I can!
-Spencer
I hope you are having a wonderful week, and I hope that the weather where you are located is as beautiful there as it is here!