Yes, if you are just talking about best possible performance, it's "Peak Performance." Apple's spelling here is presumably intended as a pun, but we won't know exactly what their intent is until after the products are announced.

Spoiler — he ended up reselling phones from ClearCellular (https://www.clearcellular.org).

No, you get Mg(OH)2, but it's similarly inoffensive stuff.

Not quite. You are left with Mg(OH)2. Commonly used in antacids. The paste seems to have less environmental impact than lithium ion battery waste or the products of hyrocarbon combustion, its two obvious competitors. I'm not sure how you remove the paste residue from the tank though; that's not discussed in the white paper.