I'm afraid not. It it better to test before you buy them or you can buy them if the shop allows you to return them if they won't work within a period...

Blinking powerline led means that the adapter is transferring data...That's normal... Any problem with your internet connection?

They are compatible with each other indeed... No worries... Pairing guidance: http://www.tp-link.com/en/faq-258.html

How did you set each device with a specific name corresponding to its IP address? Where did you "ping nas.local" or "ping 192.168.1.XXX"?

When it happens, how about status of all lights on front panel of W8961ND? You may take it to service center to test.

I'm afraid not... I didn't realize that's what you are trying to do... Is it possible for re-locate the ADSL modem router? Now in house 2, can you pick up the Wi-Fi signal from house 1? Maybe you...