Hey Jim, that '40 is really nice. An easy and effective way to fix those runs is to grind 'em out, leaving the surrounding areas kinda rough and applying one of several commercially available rusting compounds to give it that "well used" look. :)
Hey Crazy Jim, try them cotton gloves. If one of them purdy, shiny builds of yours slips and falls on the floor you may have to make a weathered, rusty wreck out of it. You may even like it. :)
Nice introduction for the unknown modeler. There is a chance that our builds could, might, or will wind up in same situation one day. Keep them around to enjoy
The paint would be thinned w/water. The mineral spirits will work for thinning and cleaning of real "enamel" paints. The "safer thinner" is one that I'm not too familiar with but probably would not try it. Why not just use WalMarts house brand or Krylon spray cans? They can be decanted for airbrush, and cleaned-up with mineral spirits