why is cash bad?
When I bought my Passat, I used one of those ZERO % interest credit card offers. It took them 5-7 business days to transfer the cash to my account. I gave the dealer a check, explained the situation and asked that he sit on the check for 7 business days. he agreed. when the cash hit my bank account, 4 days later, i withdrew the cash, handed it over to the dealer and got me check back.
paying off the car at $1,000 a month, no interest.
edit: also, most dealers... even small ones... work together with finanacing companies. if you need to go that route. and in answer to your second question... i think it depends on your state. from what the guy where i got my car said, he needed to get signatures on three different AS IS warranty release forms to protect himself. He said that NJ regulation requires it for him in a CYA move.