I have checked with my sources on these rumors and I can exclusively confirm the following:
- Yavin's moon Yavin 4 is featured prominently in a Disney Star Wars film.
- Maz has indeed played some role in acquiring Luke's saber prior to it's appearance in The Force Awakens. I cannot confirm the Lando rumors.
- Rey will possibly look different than she did in TFA or TLJ.
- The main trio will feature prominently in the film and most likely adventure in some capacity.
- While I cannot yet confirm Lucas's direct involvement in IX, I have heard he has had significant input into shaping the universe.