Commercial drivers licenses are regulated and issued by individual states. The requirements vary slightly from state to state. For example. in California a Class C license lets you drive any two axle vehicle up to 26,000 GVWR (gross vehicle weight rating), a 3 axle vehicle up to 6,000, a housecar up to 40 feet. You must check the motor vehicle regulations in the state you are planning to obtain a license.
A vehicle of less than 6000 lbs.
A Class D license permits a person to drive any single vehicle, provisionally, with weight restrictions. For example any vehicle not exceeding 26,000 pounds is allowed to be driven.
Anyone with a proper drivers license may operate the vehicle the license is for regardless of the number of passengers the vehicle may carry. For example a standard Class F license permits the holder to operate any light truck, passenger van, or passenger car, regardless of the passengers present in those vehicles.
A class a cdl license allows someone to drive a heavy vehicle with a gross vehicle weight (GVW) of 26,000 or more pounds. Example: 18 Wheeler
An International Driving License (IDL) is an identity document which permits its holder to drive a personal motor vehicle in any other country that recognizes the IDL.
You can't drive any class of vehicle that way. If you don't have the licence, or else a permit and an appropriately licenced driver with you, you can't drive it.
Whether a vehicle has air, hydraulic, or air-over-hydraulic brakes has zero determination on the class of license required to operate it.
Sixteen with permits, eighteen with drivers license.
If you don't have a CDL, you can't operate a commercial vehicle. You can't even so much as be in actual physical control of the vehicle (in the driver's seat with the motor running). Even if you possess a non-CDL Class A or B licence, this holds true - a non-CDL Class A/B only permits you to operate vehicles which fall under the exemptions for CDL requirements.
A license, a vehicle, and insurance.
Class A, both in the case of commercial and non-commercial licences permits the operator to drive combinations over 26,000 lbs. GVWR, in which the vehicle in tow is rated at greater than 10,000 lbs. A Class A CDL doesn't necessarily allow you to drive a tractor-trailer - if you don't road test on one, but rather, some other combination which falls within Class A CDL requirements (for example, Ford F650 and a trailer rated at over 10,000 lbs), you'll get an "8" restriction - No tractor-trailers.
No, because there is no such thing as an air brake endorsement on a US license.
It depends on what class the vehicle is. There are certain weight limits and it makes up the various classes for the truck. If it is a big truck you will need a commercial drivers license to be able to drive it just a mile down the road. Check and see what class the vehicle is and then you will know if you need a cdl.