As far as I know the dinner is scheduled for July. I think its on the 25th so obviously there are no updates so far. But one of Justin's agenda is to try to persuade Warren to make a U-turn on crypto so we will see.
Yes it will be held on July 25.
It's just a marketing gimmick. There's nothing to it other than him hoping the publicity will lead to more interest in his coin. Of course, I could be wrong, but that's what it looks like.
It's a gimmick for Justin Sun and we don't know his true intention but we have an idea that he's just going to shill his BTT and TRON. But I'm hopeful that he'll explain to Warren Buffett on how good cryptocurrencies are, of course not all of them but with the few chosen.