The wisest and thriftiest course is to pay cash for your cars. If this is not an option, I highly recommend you obtain financing before you settle on a particular vehicle. Negotiate for car and financing separately. Rebates go to you, not to the dealer.
Credit insurance is probably unnecessary.
Renting Money - As I mentioned , I recommend against borrowing money to buy a car. If something costs more than we can afford, we shouldn't buy it. I drive cars that cost LESS than I can afford. For example, my dream car is a 2000 Mercedes-Benz CL500. I know I could buy one, providing I financed the purchase through Mercedes-Benz credit.