a $45 per yard delivey fee is theft pure and simple. The fee should be $50-100 flat fee per delivery and if they cant deliver 5 yards all at once then they have no buisness offering a delivery.
just add 1 teaspoon to the feed once a week, if the birds have mites then dust them and sprinkle some on the bedding. if they don't have mites but your playing it safe then sprinkle it all over the coop and place in the bedding and there shouldn't be any problems. the DE is really small grains...
depends on your location but for food grade look at your local farm supply. i.e. orchelns, tractor supply, ect. you can find non food grade at most lowes home improvement stores
I actually knew about food grade diamastus earth but only for pest control on pets and to lay around the house to keep bugs out. Thanks for the additional knowledge of its use.
Also look into PDZ a horse barn freshener, I read a post here on BYC about making trays with it and it cleans up like sand and keeps the coop smelling good.