Make sure you have the latest firmware - older ones were substantially poorer in payload throughput.

Simply speaking: Raw line bandwidth does not equal payload throughput.

Same here. I've used the old PLC utility that came on CD with the adapter. That worked - and the downloadable tpPLC utility still doesn't to this day.

That "powersave mode" does not pull down the powerline network, it just sends the local LAN circuitry to sleep. So yes, the PLC on the router will never sleep simply because the router never sleeps.

Just plug the WLAN-enabled PLC wherever you need it, and make it join the powerline network that you already have.

Well ... the thing is, pretty obviously, that Powerline communications use radio frequency signaling. Domestic power wiring never is shielded, so yes of course, there will be emissions. Now powerline...