The official release date is 30th so for those who aren’t accessing the pre-launch party from 23rd - you should still have access to the old reward track. I am not sure what happens within the pre-launch party? I think you can only open packs (but not play the new cards?) so the old reward track should again still stand.
No, this is not correct, the new reward track will replace the old one with the pre-expansion patch happening this Thursday the 25th.