No. Such an endorsement does not exist for US licenses.
In some instances, yes.
No.
Only if it's a: transporting hazardous materials or b: a bus designed to transport more than 15 persons (including the driver).
Only if it's carrying hazardous materials in an amount requiring it to be placarded, or if it's designed to transport more than 15 persons (including the driver).
Air brakes have absolutely ZERO determination in whether or not a vehicle requires a CDL.
In the US, no - there is no such thing as an air brake endorsement - only a restriction for CDL holders who don't pass the written air brakes test and complete the pretrip and road tests in a vehicle equipped with air brakes, which prohibits them from operating vehicles requiring a CDL which are equipped with air brakes.
go to sears
The brake fluid reservoir is located under the hood, on the firewall, drivers side.
located at the upper end of the brake pedal under dash area
Only if it's either designed to transport more than 15 persons (including the driver), or else carrying a quantity of hazardous materials which requires the display of placards under the FMCSR. In both instances, you would need at least a Class C CDL without an air brake restriction (there is no actual air brake endorsement), as well as a passenger endorsement (for a passenger bus) or hazardous materials endorsement.
Only if it's designed to carry more than 15 passengers (including the driver), or transporting an amount of hazardous material that it requires the display of placards under FMCSR.