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.
No - you do not need to have the truck running.
they help stop a bit better then unvented disc brakes therefore higher performance cars need vented brakes to stop faster where as some cars put them on just because they look better then unvented brakes.
cause there dusty
Air brakes are located in the front of a truck or trailer. There are many parts to an air brake. If you suspect a problem, you need to take your truck to get fixed.
Yes
That depends on which country you live in.
The type of vehicle is not important, but if brake pressure is failing, you need to bleed ALL the brakes.
Air brakes have absolutely NO effect on whether a vehicle requires a CDL or not.
Need make, year, model, etc.
Need to know the year.
You need a valid drivers license. Air brakes don't affect what type of license you need.
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.