My routine is:
Foam the car, let it sit.
Pressure rinse.
Foam again.
Use wash mitt with the suds from the second foam, refoam areas that may have dried.
Rinse with garden hose at full strength to sheet the water.
I do the initial foam and pressure rinse to get the chunks off dried mud etc off...
No experience there, but I added a dual hot/cold hosebib from Kohler a few tears ago. Works great. Just tee'd off the hot water line.
HC400512PX Moen 12" Hot/Cold Outdoor Sill Faucet - Faucet Depot
Chuck