You'll need to study for the General Knowledge and Combination Vehicles tests. Also, if applicable, Air Brakes.
They're all in the CDL handbook. Study it, learn it. If you're not competent enough to do that, you have no business holding a CDL.
Not sure what you mean, exactly. Class A is considered the "higher" classification, yes. If you have a Class A CDL, you can operate vehicles requiring that class of licence or any class below that. You could operate a vehicle requiring a Class B CDL, for example, but a driver with a Class B CDL wouldn't be permitted to operate a combination requiring a Class A CDL.
That depends on what class of CDL you're going for. For a Class A CDL, you'll need to study General Knowledge, Combination Vehicles, and air brakes if applicable. For a Class B CDL, you'll need to study General Knowledge and air brakes if applicable. For a Class C CDL, you'll need to study General Knowledge, air brakes if applicable, and either Hazardous Materials or Passenger Vehicles since the only instance in which you'd obtain a Class C CDL is if you were operating a vehicle under 26,001 lbs. GVWR which was either hauling hazardous materials or else was a bus designed to transport more than 15 persons (including the driver). Any endorsements you'd need will also have to be studied (e.g., hazmat, tanker, doubles and triples, passenger vehicles).
Yes there are sites that offer information on the cdl class B license and all the driving rules to obtain the license Look for ClassB CDL study Guide. Also Truck Driver Trading Schools even DeVry has online classes for commercial licenses.
CDL classes are A, B, and C - there is no Class D CDL.
Depends on which Class of CDL. A driver with a Class C CDL is not licensed on that vehicle. A driver with a Class B CDL can drive that combination only if the GVW of the trailer is less than 10,000 lbs. A driver with a Class A CDL can drive it.
Get the CDL handbook and study it.
Class 3 truck with a rollback body? No, it doesn't require a CDL.
Yes.
You can obtain a CDL class B license at your local DMV. To obtain a CDL class B license you are required to take several tests before obtaining your license.
You will need a Class B CDL with tanker endorsement.
Depends. You can drive up to a Class 6 truck (up to 26,000 lbs. GVWR) without a CDL. Class 7 or Class 8 trucks require a CDL.