Regarding salt staining...
I like your Kate...but I think you may have missed the chance for salt staining and chipping. If I totally mis-understand your intention, my apologies.
Try this link from Swanny's page. http://www.swannysmodels.com/Salting.html
It describes chipping, but I have found an interesting side effect in most cases. If you put the salt on over a regular (no future or clear coat) base metallic then lay on a flat acryllic over the salt, there will be a "staining" effect around the salt.
The other method which I used on the P47 is to use an artist's blending stump and pastels. I used it to lighten panels. The stumps are cheap, I paid $1.20 at the local art shop for a pack I will never use up.
Hope this helps.