Can a beginner driver work on getting their CDL?
You can pick up a manual from the DMV or download a copy from their site and study the material at any time. To take the test and get your CDL you need to be 18. You will only be able to drive (a commercial vehicle) within the state you live until age 21.
Go for it.
Yes. Fully understand RULES OF THE ROAD specific to your state or province residence.
Obi Wan Knievel
Depends on where you live, but most jurisdictions have minimum licensing requirements (with a 'full' licence) before you can apply for the commercial stuff. There's nothing to stop you from studying the material, though. You can do that even with no licence at all.
You can...however you need to be 18. So what are you going to do for the 2 years? You learn how to drive a car...and know the road rules.