PA2030KIT and WPA281 are compatible with each other indeed. Follow the guide below to pair them. http://www.tp-link.com/en/faq-258.html

One adapter is connected to home hub and another adapter is connected to your PC? You cannot access internet on your PC, right? What's the IP address obtained on your PC? Try to reset both of them...

Two paired powerline adapters can work like an ethernet cable, so it should be fine to connect the router and switch by powerline adapters. I didn't see a new version utility for MAC. Try the one as...

Since you've done Wi-Fi clone, powerline extender's SSID and password are the same as your router's? They should not conflict with each other. You can "see" router's Wi-Fi but cannot connect? How...

I have found no way of activating an SSH/Telnet connection to the router, do you know if it exists? It doesn't exist.

If your internet connection has no DNS issue, it is Okay to disable it. In some cases, if we cannot open domain name but the corresponding IP address, we can set the DNS relay as "Use User Discovered...