It's not a matter of state law - it's a matter of federal law.
A medical is required for anyone:
Additionally, to possess a CDL, you must possess a DOT medical card - ipso facto, if the vehicle requires a CDL, whether for interstate or intrastate commerce, the medical card is also required.
If the commercial vehicle requires a CDL to drive it, you do.
10,000 lbs. GVWR and up in a commercial use vehicle, and the answer is yes.
You're required to have a current medical card on your person at all time when you're driving a vehicle which requires a CDL. In any state. That's federal law.
Depends on what the vehicle is. A one ton pickup is a commercial vehicle if used for commercial purposes, even though it doesn't require a CDL.
No.
It is possible to obtain a CDL with diabetes, provided it's not too severe for you to be able to obtain a DOT medical card.
You can drive a vehicle home from Illinois to Indiana with temporary plates. It is important to keep your purchase paperwork with you during the travel.
No, you can get a commercial policy for a commercial vehicle. If it's for a company you work for, I would make sure they had proper insurance before you drove the vehicle.
No.
A Commercial drivers licence is the licence to drive any heavy weight vehicle. You do not need a parent in the vehicle with you when you drive on the streets. Although, you do need a parent present when you get your licence, and they have to sign the papers.
You can't drive any class of vehicle that way. If you don't have the licence, or else a permit and an appropriately licenced driver with you, you can't drive it.
Any CMV with a Gross Vehicle Weight Rating in excess of 10,000 lbs. and which is being operated across state lines requires a current and valid DOT medical card. Any vehicle under 26,000 GVW which is a bus designed to transport more than 15 persons (including the driver) requires a CDL, ergo it requires a medical card. Same with any vehicle carrying a quantity of hazardous materials which requires placards to be displayed.