It's not about absolutes. It's about averages.
Wider tires could be faster, but only on rough terrain. On smooth pavement, narrow tires are faster. Less weight, less rolling resistance, less air resistance. This isn't a matter of opinion. This is tested data.
Nope.
Once more- wider tires can be faster than narrower tires. Narrower ties can be faster than wider tires.
It all depends on tire construction, psi, tread pattern, and more.
And a wider tire can be faster than a narrower tire on good quality pavement due to lower rolling resistance. As for air resistance, a 40mm can absolutely be faster overall than a 32, even with wind resistance taken into account.
Again- it depends on the tire construction, psi, and more.
As you claimed, this is tested data.