Tests like that are made to pass. Just study for a few days and you should be good to go. The rules of the road are pretty much the same for every driver out there.
Depends on the reader and how well he or she can comprehend things like gear ratios, hill grades, electronic logs, etc..... If you were an accountant looking for a career change, it might be hard for you.
From what I hear, the written part of the CDL test isn't too difficult to pass. Just study the CDL manual thoroughly, and you should be okay. You can take a practice test online if that makes you feel better, too.