GTA: San Andrea's
1)Nope, I doubt there is such thing as a credit card in this game. It is most likely just a rumor.
2)Not sure there is a cheat for that, maybe you should browse the Cheats section in the Grand Theft Auto: San Andreas link.
3)Yep, you can put your car in a garage, fix it at a Pay n Spray or you can install a part at the Mod Shop (I suggest just changing the color)
Hope that helped
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