Void border type doesn't cut off structures or water and provides light to caves #1

I'm putting these 3 separate issues into 1, since they're fairly related. In custom worlds set with the border falloff type=void:

While the initial blocks in the void get deleted, seemingly (at least modded) structures that spawn just inside the world borders can still create their blocks outside of the world border. I'm not aware of how structure generation works but maybe there's possibility for a late generation pass after structure creation that can remove these blocks. This would probably be the most impactful change because currently it leaves a player unable to remove these void blocks if they wanted to remove or rebuild the structure.

Water that borders the void such as an ocean starts flowing one block into the void due to the void itself being seemingly air. Maybe it is possible to create a border just inside the void made out of barrier blocks to prevent these edge cases. While the flowing water at edges looks ugly, it's always still removable by a player if they get rid of the source blocks.

Lastly caves inside the ground that border the void get lit up, i'm not sure if there is any solution for this since i think barrier blocks still permit light, and while i believe these caves bordering void in PE were unlit, i think it's insubstantial enough to ignore.