Have a look at FMCSA's website specifically surrounding the rules for drivers, as well as the rules that carriers must follow in regard to their drivers. I believe it outlines what info must be obtained on a driver before they are brought into a fleet, as well as what they need to do to keep the driver files current. Some rules are for all drivers, while some relate more to what the driver is driving (size of vehicle). On top of FMCSA's rules, insurance companies have their own set of wants, and carriers will have their own set. They might be different again depending on whether one crosses the border or not, or carries hazmat, etc.
I'm sure you'll receive more specific answers from many others if you can elaborate on what you're looking for.