> What’s required for an impeccable streaming setup?
> 1) Good lighting that can be precisely calibrated, both in brightness and in colour temperature
For most uses, fixed brightness is fine as long as you can adjust the light's distance. Lighting doesn't need to be color-temperature adjustable because that's what the white balance on your camera is for -- just make sure all your lights are the same color temperature. Mostly, just get a single large ring light, about $90. [1]
> 2) A good camera with a big sensor and a wide aperture lens
If you've got good lighting, then no -- honestly an $80 Logitech C920 [2] will be perfectly adequate for sharp 1080p, and over videoconferencing it's going into deeply compressed 720p anyways so it's more than enough. A wide aperture lens is only if you want a blurry background, which is almost never desirable in professional interviews or videoconferencing. (Gates has a blurry background, this is very unusual.)
A large sensor/aperture is required for low-light conditions, but you should be using good lighting, so that shouldn't be an issue.
> 3) A good microphone
It doesn't need to be that good, just better than your built-in laptop mic, or built-in Bluetooth earphones mic. A $40 Blue Snowball iCE [3] will be more than enough. A $35 lapel mic [4] will be pretty decent too. But just like lighting is far more important than your camera, distance to the mic is far more important than the mic itself. Generally, it should be roughly 9" away, which means keeping it just out of frame, supported by some kind of stand.
> 4) The right rigging to hold everything together
Yup, basically just a stand for your mic and maybe for your webcam. Also possibly a stand for your laptop to support it at eye level.
> 5) Ambient fill lighting
Any normal room has this, though you may need to change which direction you're facing to optimize.
> 6) The technical expertise to understand how colour temperature, shutter speed, aperture, and ISO conspire together to form a beautiful picture.
You absolutely need to manually set the white balance and lock it. Webcams don't really have ISO (they have gain), but you absolutely do need to set the gain to zero (because you have good lighting) and lock the shutter speed for the desired exposure. Not a whole ton of technical expertise here though -- it's pretty simple.
[1] https://www.amazon.com/Neewer-Ring-Light-Kit-Self-Portrait/d...
[2] https://www.amazon.com/Logitech-Widescreen-Calling-Recording...
[3] https://www.amazon.com/Blue-Snowball-Condenser-Microphone-Ca...
[4] https://www.amazon.com/Professional-Microphone-Omnidirection...