Any time you are operating a vehicle with a Gross Combination Weight Rating of over 26,000 lbs., and in which the vehicle in tow (trailer) has a Gross Vehicle Weight Rating of over 10,000 lbs. A tractor trailer requires a Class A CDL. A truck rated at 26,000 lbs. which is towing an equipment trailer rated at more than 10,000 lbs. would require a Class A CDL, as well.
This does not apply to vehicles which are not the jurisdiction of the FMCSA, such as:
You will need a Class B CDL with tanker endorsement.
Class 3 truck with a rollback body? No, it doesn't require a CDL.
No, you do not.
No. The weight determines what class licence you must obtain (there are non-CDL Class A and B licences available), and the usage is what determines whether or not you actually need a CDL class licence to operate it.
You will need a Comercial Class Drivers License. This is usually a Class A CDL in most States. So you will need CDL training.
You would need a Class A CDL for Dump Truck. It's not as intense as more restrictive classes of CDL.
Yes, you would. Without the trailer, you could operate it with either a Class A or Class B CDL.
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.
Yes. In most cases you will need a CDL Class B license because of the weight of the truck. However, if you would be driving a semi with a dump trailer, you would need a CDL Class A license.
Depends on what class of CDL you're going for, among other things.
Yes. You can drive that vehicle with either a Class B or Class 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.