that looks about right. The metal ready will convert any rust, even the slightest, into that white powdery substance you see.
As long as it doesn't come off on your hand like chalk from a chalkboard you are ok. If you brush your hand on it and get a lot of the white powder, it means you should rinse it more. You can also wipe it with a wet rag. If you leave it too powdery, the paint won't grip as well. Don't stress about it though, you should be fine.
As for the overspray... the metal ready is kind of a corrossive agent. I would clean as much of it off of your internal parts as possible just to be on the safe side.