1) Cheat. I'm sorry to be the bearer of bad news, but that's the only way to do it. The credit counter, if you're unfortunate enough to try to earn so much, stops at 999,999,990 cp. They limited the counter for english versions, I suppose to compact the code elsewhere, so that means you need a gameshark or codebreaker or something.
2) I don't believe the years are listed anywhere, but you should be able to recognize a car from the '80s on your own. However, I'll try to give you help: The Sprinter Trueno, Corolla Levin, Subaru Alcyone, Izuzu Piazza, the Mitsubishi Lancer 1600, will all do the job. Basically, though, you could probably look at a car and see if it's from the '80s, because that's the time when the boxiest-looking cars existed.
