Jon, that's a lot of stuff I haven't had to think about - does your Internet/ethernet run through the power lines? (The "mains" you call them?) That would be nice. We have to run the Cat 5, or now Cat 6, for all Internet connections (unless it's WiFi), completely separate from the electrical part of the wiring.

I have one smart bulb that I've not yet decided on placement. It's the same brand as the smart bulb I have in my kitchen dining area so they can be installed on that one app. I tell Alexa to turn it on and off and don't need to lean way around the corner to reach that switch (put in the wrong place to begin with, and I'm not paying to rewire it). This second bulb is here as a spare since I haven't had a use for it so far. (I have Alexa in the phone but purposely haven't turned it on; I use an Echo dot in two rooms for the command to the bulb or listening to radio.)

I buy the LED fixtures now, some encased in bulbs, others with the bare diode inside the fixture that is put up in the hall, the laundry room, etc, in place of a dead fixture. I need a new one for the side porch where I used to use the stick halogen bulbs. Next iteration will be LEDs.