You can block invitehawk.com. Since the site is on HTTPS, it’s not possible to block a particular path without breaking the encryption. And we don’t want to break encryption.
1). You can use the same SSID for the TP Link powerline adapter. I.e., both WiFi SSIDs can be named “pcwrt”. Use the same password for both too. Your device will pick the stronger signal and connect to it.
@casino Sorry for the late reply. You should connect one of the pair to the pcWRT router by wire. The other one of the pair will provide WiFi in a remote location. When you connect a device to the WiFi provided by the powerline adapter, you should be able to see the device on the Status screen of the pcWRT.