As other comments point out, the sphere would have immediately vaporized. Similar reason behind most impact craters being circular. Scott Manley has a nice explainer: https://www.youtube.com/watch?v=BCGWGJOUjHY
I would guess so (like a bullet). I suspect they placed a second ball for illustration.
I think you are correct. The original ball is what appears like a paint splatter inside the deformed area.
It's probably not the aluminum sphere that was used in the impact but included for reference to allow readers to visualize the effect of impact versus the size of the debris.
I assume they put another sphere in the hole for the purposes of the picture.
As other have said it's likely a second sphere there for illustration purposes. Also, I wonder if the original sphere would outright vaporize or melt into the block.