Pretty sure Paul used to use a zymol sponge (not watched the video) but these are synthetic sponges and I have used these on soft finishes without issues, not cheap though and always hard to get hold of.
Kyle your spot on bud, I always recommend the citrus pre wash as opposed to foam and people who have sworn by snow foam for years always come back and comment how the citrus pre wash removes so much more dirt.
That's a brilliant repair,like you say when having a bumper redone if the place is good,you actually get a better match than from the factory but that's very impressive on pearl.