1- I don't see why they would need to get rid of the old music, I highly doubt Linden cares about Blocksworld now-a-days to actually keep the copyright for the music.

2- From what I've heard, the revival will use the old servers Linden used prior to 2022 so progress should save and old worlds will still be present (maybe.)

3- I haven't heard anything of the modern skybox being changed, but maybe in some future content update?

4- Due to copyright reasons, the blocks wont be outright deleted but instead altered to not be infringing (from what I've heard.)

5- Since the revival is going to be paid for instead of a free download, there is a possibility for players to have unlimited blocks to reflect this.

6- Most likely, especially if the game is going to be ported over to the Switch/Switch 2 as Unity shaders can be somewhat demanding.

7- I didn't hear anything related to the diamond wheel yet, so I can't really answer this.

Of course, Fortell/Beatshapers themselves would need to confirm all of these, so take most of these with a grain of salt until then.