New York State requires anyone operating a for-hire vehicle with a gross weight of over 18,000 lbs. within the state of New York to get a CDL for that vehicle - they are the only state to do such.
Other than that, the only circumstances in which a CDL would be required (whether it had air brakes or not - the presence or absence of air brakes has no impact on whether or not that vehicle needs a CDL) is if it's a bus designed to transport more than 15 persons (including the driver), or if it's carrying a quantity of hazardous materials which requires the display of placards.
No.
Air brakes have absolutely ZERO determination in whether or not a vehicle requires a CDL.
To answer you we need to know what country's traffic regulations you are asking about.
Only if it's a: transporting hazardous materials or b: a bus designed to transport more than 15 persons (including the driver).
Not unless it's a bus designed to transport more than 15 passengers (including the driver).
No
Only if it's hauling hazmat or is a bus designed to transport more than 15 passengers (including the driver). Air brakes have absolutely nothing to do with whether or not a vehicle requires a CDL.
Only if it's transporting 16 or more persons (including the driver) or sufficient quantities of hazardous material to require placarding with HAZMAT warning signs.
Yes
That depends on which country you live in.
No, unless you're hauling something which requires a hazmat endorsement, such as contaminated soil.
Air brakes have absolutely NO effect on whether a vehicle requires a CDL or not.