As JPC say, the Valet Pro is perfectly safe on all surfaces and is completely wax friendly so it won't strip off any of your hard work!
When you have a lance attached to the pressure washer it does somewhat reduce the pressure, so you can get quite close to the car without any worries, although we wouldn't recommend getting too close!
Hosing off with water shouldn't be a problem, the one benefit to pressure washing off though is that all of the surface dirt that's been lifted by the foam is easily washed away under some pressure, but I can't see you having too much trouble just hosing them off!
Hope this helps
Jim