I was looking for information like that when I last bought a TV in February and couldn't find anything.

I punted and bought a SAMSUNG 65-Inch Class Crystal UHD 4K CU8000 Series (that's like 1/4 of the amazon title) and have not connected it to the internet at all. As far as not being connected to the network, it's… fine.

• There have been no issues with it trying to lock me out of features.
• I didn't try to opt-out, but my intuition tells me that's unlikely.
• No camera that I know of. I think there's a microphone in the remote, but I've never used it, and since I've never connected it to the internet (and I never use the remote) I don't really worry about it.
• I've not experienced any nag screens.
• I have not measured the power usage directly (and would have nothing to compare it to since I'm not willing to connect it to the internet even as an experiment) but I do have it connected to a power-usage sensing outlet strip and it uses dramatically less power than my previous Samsung 42" HD LCD (with florescent backlighting.) So much so that for it to not turn off the switched outlets I had to add my AppleTV to the control outlet (and for extended dark scenes even that's not enough.)
• If it's connecting to networks surreptitiously I would expect to start seeing ads or some change in behavior, which hasn't happened, so I'm going to say probably not.

As far as how good of a TV it is, (which you didn't ask, but since I'm here):
I'm not the most discerning viewer, but I think it's got a good picture. Sometimes I can see the backlight adjust itself on very dark scenes, but it's hardly a show stopper. I have an external speaker system, so really the only thing I do is turn it on and off (with the AppleTV remote). My only other gripe is that it takes a few seconds to decide to display the selected input full screen.