Transferring to the computer is easy! If you have a USB flash drive, you can plug it into the PS2 (first slot) and save the images directly to it. It will make a folder on the drive with .jpg images in it. Then it's just copy & paste somewhere on your computer!
The way I got all those cars (and more now
) is by playing the Special Conditions races (to the left on the menu). Do the second races (Costa di Amalfi) - they're very easy, I won by like 30s with my RS4 when I did it first... You'll win a Toyota rally car (268,000 cr.) and 10,000 cr. total (5,000 cr. per forward & back).
If you do the first races in there, you'll win the Cadillac Cien (can't sell for cr.), and the third set will win you a worthless rally car. All the "easy" level races actually are easy in there, so have at it!