Depends on what endorsements you have. If you have none, then you really won't be able to drive anything other than what you could drive with a non-commercial Class C licence.
If you have a Hazmat endorsement, then you can drive a vehicle up to (but not exceeding) 26,000 lbs. GVWR, and carrying hazardous materials in a quantity sufficient to require placards to be displayed.
If you have a Passenger endorsement, then you can drive any vehicle up to a GVWR of (but not exceeding) 26,000 lbs, and designed to transport more than 15 persons (including the driver).
You cannot get a doubles endorsement with a Class C licence, you cannot tow a trailer rated at over 10,000 lbs, and you must still take the air brakes test to be eligible to operate a vehicle with air brakes in a commercial capacity.
So long as you don't have the "no air brakes" or "no tractor-trailers" restriction, you're pretty much licensed for anything which can be on the road. Doesn't necessarily mean you're qualified, but you are licensed.
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.
You will need a Comercial Class Drivers License. This is usually a Class A CDL in most States. So you will need CDL training.
What exactly is a "mini-Peterbilt", may I ask? If you're referring to pickup trucks with aftermarket bodies designed to look like Class 8 trucks, then no, you don't need a CDL for that.
No. U-Haul doesn't rent out trucks higher than Class 6, which have a GVWR under the weight requirements for a CDL.
Class C CDL with School Bus endorsement.
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.
Class C CDL with School Bus endorsement.
A CDL or comercial drivers license allows drivers to drive taxis, minibuses, lorries and trucks. This license includes pallet trucks and any driver wishing to drive a pallet truck must have a CDL.
Yes.....
Yes.
Yes. You can drive that vehicle with either a Class B or Class A CDL.
No. Just to drive it (if it requires a CDL - not all trucks considered commercial require one).