If they are a resident in the United States, if they possess a green card, and if they possess a valid work visa, then yes.
A Canadian citizen with a Class I can also operate in the US, and I have seen some who, while maintaining their residence in Canada, have worked for US carriers.
CDL stands for Commercial Drivers Licence. It's the licence you must hold to operate a CMV. CMV stands for Commercial Motor Vehicle, and is the vehicle itself.
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.
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.
A CDL does not permit you to operate a motorcycle. You must get a motorcycle endorsement on your licence - regardless of what class or type - to be able to ride a motorcycle.
Not necessarily, although you do need the appropriate class licence to actually operate it. You can operate anything up to 26,000 lbs. GVWR on a standard Class C licence. Anything above that, you either need a non-CDL Class B or A licence, or a Class A or B CDL, depending on what type of truck it is specifically, and if its use permits it to fall within any of the exceptions for requiring an actual CDL (registered farm vehicle, etc).
No. Motor homes are exempted from CDL requirements (for better or worse). Some states, however, may require residents to obtain a non-commercial equivalent licence (Class A or B) for non-commercial vehicles matching the weight requirements for the equivalent CDL licence.
No. You only need a drivers licence to operate equipment if it's plated for use on public roadways.
If I'm interpreting this correctly, you're asking if you can downgrade a suspended CDL and be able to drive on a regular operator's licence. It does not work that way. While the suspension period on any licence is active, you may not acquire or possess any other class of licence, nor operate a vehicle on any other class of licence. If you wish to downgrade your CDL, you will have to wait until you have met the criteria to restore your licence and driving privilege, then request a downgraded licence at the DMV once you have done this.
If you don't have a CDL, you can't operate a commercial vehicle. You can't even so much as be in actual physical control of the vehicle (in the driver's seat with the motor running). Even if you possess a non-CDL Class A or B licence, this holds true - a non-CDL Class A/B only permits you to operate vehicles which fall under the exemptions for CDL requirements.
Commercial Drivers Licence
Commercial Drivers Licence
No, you cannot. Canada is part of the ICC, and shares commercial driver information with the American FMCSA. If you try obtaining a US licence while possessing a Canadian one, or vice versa, they'll find out about it. By the way, "CDL" is a term exclusive to the US.. Canada uses a different system. Class 1 is the equivalent to a Class A CDL, Class 2 is equivalent to a Class B, and I believe Class 3 is for buses and such.