Calculator bullshit is due to the animation of the button, and it will only show if you're really fast trying to calculate things. There are better third party calculator apps that don't have that problem and contain more features.

The wifi part, I did notice it. But, I think it's by design. When you're connected to wifi, click the wifi button on control center just disconnects your current wifi session. I've actually kinda grown to use that feature. I don't like hooking to xfinity hotspots much, so I click that away. When I get back home, phone automatically hooks back up to my wifi.

UX hell in iphone X... don't get iphone X. Or any OLED screens with burn-in issues.

If you go into settings and turn Wifi off it is completely off. Turning it off from control centre is a useful alternative where it disconnects, but leaves it available for geolocation and airdrop - it's really rather useful.

This sounds terrible. Why not having it op-in? I'd expect that I'll need to go to settings and add it to the functionality of the control center button.

I suspect because Apple found out that people were primarily using the Control Centre switch for 'This WiFi network sucks get me off it' reasons, rather than 'Disable all Wifi circuitry reasons', so optimised functionality for the use that users were using it for.