Excellent write up, and a perfect example of why I don't bother with pre-washing at all. I used to use the foam, but all it did was add time when a quick rinse with a hose does pretty much exactly the same thing.
I don't even bother with the jet wash any more, unless I'm doing the arches (any car) or the front rads (on the 911). For me, all it does is add time and a proper contact wash with a good shampoo and wash mitt gives a billionty percent better result.
All IMHO, not knocking you at all Ilogikal as I find your take on detailing fascinating and I've picked up more than a good few hints off you over the years