I'm not sure how the rental companies process an incident. If you proceed with using a CC for the CDW contact them to make sure if they still offer it. Many companies have discontinued that perk. If you elect to purchase the collision and liability from the rental company to include other drivers it will get expensive. As far as Liability some companies, like Hertz SXM, include this free for driver and spouse but not collision. There is a fee for additional drivers. What ever you do be sure and get a quote that includes all fees, taxes and insurance charges to avoid any add on surprises at pickup time.