Bikes do not have VIN numbers. They have serial numbers. Serial numbers have much less information on them than a VIN number. In the case of Schwinn, the serial number will tell you year and month basically. Its kind of sad bicycles do not come with VIN numbers.
Generally, the boys style bikes have all the value, and the Krate style much more so. Girls style bikes can end up being donor bikes for boys bikes.
+100 Original paint even with defects will tend to be more desired than a repaint. And getting a repaint "right" along with the decals can be challenging. There is a Schwinn specific forum out there, where you will get more information. Not much on this forum pertaining to children's bikes.
Endless threads on how to handle rust, I've treated rust on many hundreds of bikes, along with a lot of parts. So far, I have never repainted a bike.