The first part is most likely Lucas revisionism i agree, but Star Wars a New Hope goes back to November of 1979. In the first edition of the art of star wars. But yeah it was only spliced into prints with a new rollup and starfield in 1981.
Some things do go way back. Some fans insist Sith was created on the prequels. But it goes back to the 1976 Novelization where Darth Vader was a Dark Lord of the Sith.
As for midichlorians i still believe those were created during the prequels and Rinzler will never convince me otherwise.