Hi, my names Mark. Sorry I don't have any experience with the snowfoam kit and given that your car is mainly for fair weather drying I would only use the pressure washer for very stubborn dirt and for wheels/under arches.
I prefer to use a normal hose and wash mitt.
A regular coat of wax on the paint will allow dirt to come off easier with just a normal hose.
I will definately be booking in with you next time my car is down at the SL shop. I have seen the quality of work not only on my car but also on the other SL'S in the showroom there.
I am dying to wash the car but weather is so awful right now. Also one thing that worries me washing is the fact the SEC'S are known to allow water in but i think my car is water tight now after having all drainage areas cleaned out etc.
As for the pressure washer i will have to think about it as i love using that to blast away the dirt. haha