Well, there are three questions to ask of you here..
If the answer to all three is "no", then not a thing. Air brakes do not require a CDL.
juggernaut
Pneumatic schematic in the air brakes in any type or build of truck all work in coordination with each other for smooth driving. The brakes would not be able to smoothly stop without them.
Slow down, don't slam on the brakes. Pretty much the same as driving any other truck. If it's empty, be especially careful (well, you should always be especially careful driving in snow, but anyhow..)
You need a valid drivers license. Air brakes don't affect what type of license you need.
This is a tricky one. The GVWR doesn't call for anything but a Class C driver's license--the cutoff for that is 26,001 pounds--but this truck has air brakes and you're driving it as part of your job--maybe your whole job. If I was driving this truck I'd want a Class B CDL and I'd take the air brakes test.
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.
Quick Service brakes and parking brakes.
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.
This varies based on the model of truck. First determine if your truck has drum brakes or disc brakes. See related questions and links for more specific details on replacing brakes for specific models of Ford trucks.
Yes. However, the truck must be wired for a trailer equipped with electric brakes.
No - you do not need to have the truck running.
That depends on what type of transmission you have. The truck having air brakes doesn't affect that.