Id be using them on my tires and thats about all, maybe the engine bay. Use a proper wash mitt on your painted surfaces
depends on the brush, I use the swissvax brushes on the paint work around emblems etc, I use them also on trim; rubber or metal. Never had an issue. As with anything depends on the skill and technique. Example being if you are doing around emblems, or door jambs, both considered painted surfaces the paint and the brush need to be wet or lubricated with soapy water, apc or whatever it is you are working with. I have a boars hair brush on a extended pole to wash my suburban, no issues with marring, again YMMV depending on the lubricity of your soap and how much soap you use.
