Nope, I do have the ingredients for it somewhere. I never bothered with it because the cost per roll for C41 bleach turns out to be so ridiculously low that any effort spent on trying to beat that seemed counterproductive to me. C41 bleach basically lasts forever and can be replenished easily. I really wouldn't bother trying to DIY it.
There are several posts here on this forum that detail how you can preserve your C41 developer. Even if you buy relatively small (and therefore relatively expensive, on a per-liter basis) volumes, these approaches work.
I think if you run the numbers, you'll realize (like many before you) that DIY-ing this chemistry only makes sense if you live in a location where commercial options are unavailable or prohibitively expensive, or if you're trying to hedge against a contingency where commercial chemistry becomes entirely unavailable. We sometimes see people in e.g. South American countries DIY-ing color chemistry for the former purpose.
No, it's a different mechanism. PE seems to be referring to the effects of incomplete bleaching, i.e. retained silver. That's also a concern, but more so in film (esp. slide film) than in paper - although of course in paper it's also undesirable. There's just not a whole lot of silver in paper so it generally blixes out fairly easily.
