As already posted, I would go with the 2 bucket method using Meguiars products, microfibre wash mitt, with thick microfibre cloths to dry.
I've heard that Wonder Wheels has a very strong acid content, again Meguiars products for the alloy's.
As for the pressure washer thing, If Paul Dalton (Miracle Detail) uses one on a Bugatti Veryon, then it should be safe on my Mini.
Have a look at
A world for detailers..., so much to learn from there. A lot of real pro's at the cleaning game, but they will answer any questions. Also a lot of amazing details in the 'show it off' section, some seriously clean cars
Good luck
