Yes buy it at counter at time of renting
YES, Rental companies do not ask for proof of insurance. But I would consider taking he rental cars protection package out.
If you don't have the licence or the insurance, no
You can get a car insurance unless you will buy a car.
In California you have to be at least 25 years old to rent a car. Insurance companies will not give an 18 year old rental car insurance. If you do find a rental car company that will allow you to rent a car from them, the insurance you have on your own vehicle will cover the rental car as well.
Some insurance agencies will let you get a sort of temporary coverage, but I'm pretty sure you can't get permanent car insurance for a car you don't own yourself.
Depends, you have to ask your insurance company
No, unfortunately your own car insurance does not cover your budget truck rental. However, when you rent the truck there should be rental insurance available.
If you want to rent a car, you need to check with your own insurance provider and see if you are covered. If not, you can purchase the insurance from the rental company directly.
insurance on a home you own and rent out
If the car if financed, the lender will require you to insure it. If you own the car, and don't drive it, you are not required to have insurance.