Once DE gets wet it no longer works as insect control.
Using the the wrong form of DE around your chickens will kill them over time. Anything other than codex (food grade) DE is poison. It must be food grade DE not gardening DE.
Gardening DE will poison your chickens over time. Don't use it.
White wash is made from chalk and Lime. Some times you will find water downed paint refered to as whitewash. One thing it does it makes things look cleaner and you are better able to see dirt and areas that need to be tended to.