Due to the nature of resin, our models should be treated carefully. They can be handled casually when playing, but falling even from table height can result in a broken piece. In most cases a tiny drop of super glue should be able to remedy the problem and fix the breakage.
Our 3d printed models are created by UV lights curing the liquid resin into the shape of the models. As such, direct sunlight will further cure the models and can lead to cracks or other problems. Some sunlight won't hurt them, but extended time could create issues. We cannot speak to what would happen if a box containing our models was kept in a car on a hot day, nor if being painted will create a resistance to sunlight. Our recommendation would be that you avoid both as much as possible.
All of our models should not require washing prior to priming or painting. In our experience we have not encountered any miniature paint that has had an issue adhering to our models. Craft paints will likely have problems as they do with other miniatures from other businesses.