1) It's at
?t=628. Ultrawhite paint is 88.6%, a silvered mirror is 89.5%.
2) Don't know
3) [citation needed]
4) Disagree. It's reflecting the heat load rather than cooling it.
The part significant to me is the mechanism, a three part precursor, a phase inversion, then washing one part, sintering away the other leaving an aluminum aerogel.
The resulting aluminum plate is white because of it's nanoscale structure not pigment. I suspect it's similar to the vacuum airship 'tic-tac' drones the Navy pilots are reporting offshore of California and Florida.