Not necessarily. If the vehicle is under 26,000 lbs., and is not carrying sufficient quantities of hazardous material to require the display of placards, and is not designed to transport more than 15 persons (driver included), it's not considered a commercial vehicle, whether or not it has air brakes, and the only times you would need a CDL for such a vehicle is if it were carrying hazmat or if it were a bus designed to transport more than 15 persons.
That depends on which country you live in.
Yes
Air brakes have absolutely NO effect on whether a vehicle requires a CDL or not.
No - you do not need to have the truck running.
You need the license to drive a truck and then you need to apply at a company that searches for truck driver. They will tell you if they need somebody or not.
You need to replace the rear brake pads and anything else the brakes may need. Driving without rear brakes would be foolish and dangerous. Good brakes are a number one priority.
The braking system doesn't determine whether or not a vehicle requires a CDL.
Whether a vehicle has air, hydraulic, or air-over-hydraulic brakes has zero determination on the class of license required to operate it.
To drive a semi truck, you need a specific driving license that allows you to drive that class of vehicle. As well, as proper education and training such as driver's ed.
Brakes will be dependent upon what type of truck you have and what you are doing with your truck. There is a website that can help brakeworld.com will help walk you through the right selection of high performance brakes for your truck.
Air brakes have absolutely no determination on whether or not a vehicle requires a CDL. Zip. Zilch. Nada. Not just in Maryland, but in any state.
If you rent a bucket truck you may not need one. However, if you are to drive one for work they may require you to take a safety course since a bucket truck is one of the most complicated pieces of equipment the company has.