Okay, I managed to resolve the above Hub issue by directing my phone to forget my wifi network and reconnecting to wifi again, as recommended by Hue Bridge Connectivity Issues (huetips .com).
I really don’t know if the Hub is required for the Echo Plus or not. It certainly seems that way based on my experience thus far, but there was enough weirdness with the Hub not being accessible for awhile and the meethue.com website, which the Alexa app directed me to in order to get started on its hub functions, saying that it required that I turn on a Hue Hub, all of which make me think that something is really off with Amazon’s product description saying “No additional hub required”.
In order for me to actually get to the bottom of this, I would have to spend yet another hour or two restoring devices to factory defaults and rediscovering bulbs and renaming them and recreating room groups all over again, which I don’t have the energy to deal with right now. So I’ll just stick with things as they are.
So, as for the Echo Plus, it’s just a more expensive Echo in my opinion, although it does have a 0.8" tweeter versus the 0.6" tweeter on the standard Echo. I have heard people say that it also sacrifices bass for treble, but I don’t blast my music and am not noticing that yet and may not ever notice it.