@falconscastle,

Essentially you are looking to connect a wireless AP to a Powerline Extender to extend the wireless network and provide connections for wired devices.

Yes, this is possible, but all of the traffic passing through the router(AP) will be limited by the Powerline connection you are able to provide. If this will be a source of internet for a large majority of devices in your home, you may experience difficulties, depending on the quality of your Powerline Network - But it is very possible to set up in this way.

There are specific powerline adapters that will also provide a wireless signal for your devices, which may be more convenient.

If you are only looking to provide a wired connection to devices, you should have no problem using just a switch to extend the wired connections of the Powerline extender.