@PhilShelley 

Hi, for AV2000, I guess you mean TL-PA9020P KIT or TL-WPA9610 KIT, and 16 nodes can be added into the same powerline network, you could also refer to the FAQ below:

How many Powerline adapters can be added to the same network?

By serial number, do you mean model number? Because the serial number is different for each powerline device.

In addition, in theory, it should be okay to use under the same board, but it is recommended to use them within the same ring circuit, because there might be some filters between different ring circuits which will block the powerline communication. After you purchase some of them, you could test if they will work in different circuits in your house.

  @PhilShelley 

Hi, may I know the bandwidth you paid and the internet speed you could get from your router? And do you need WiFi functions on the powerline units?

You could select the models based on your needs on our official website: Powerline Adapter - Powerline Ethernet Networking

Note: For the WiFi Powerline KIT, it contains a wired powerline adapter and a wireless powerline extender, instead of two wireless powerline extenders. For example such as TL-WPA8631P KIT contains a TL-PA8010P and TL-WPA8631P.

While for wired powerline KIT, both units are wired powerline adapter. For example, TL-PA9020P KIT contains two TL-PA9020P.