I have a Kahr cw40 that I used that stuff on. It is the two tone model (i dont know if they make one that isn't). There was never any rust or anything on the slide. Now, there is freckling of rust on it. I have not been keeping it in a damp place or anything, so I am a little confused. I am also not saying 100% that the weapons shield is the cause, but it seems like a pretty big coincidence. It did not do it to my sig c3 though.
No, and it wipes off easily. The wood is a little more glossy and feels so smooth after wiping off the excess with a dry towel.