Some 10+ years ago, my daughter, her husband, and 3 kids moved in due to, well, 3 kids got expensive. So for about a year, my daughter did the dishes with the new Kitchenaid dishwasher. One day she comes to me and says, "look at all this grey stuff in the dishwasher!" Inside of the machine was all coated with mineral deposits like I had never seen! I carefully scraped it out. I filled a fruit jar with the stuff. After that, I use 'Lemi Shine' with each wash and it has been great for shiny glasses and dishwear, and no more 'grey junk' in the dishwasher. (It is available at Walmart)
Just hand wash the dishes (before the lazyitis epidemic hit, this was the only way to wash them). Or, if you're super lazy, let the dog lick them clean.
No. And that's not a good idea--use too much and you'll cause it to overflow and spill out onto the floor (happened to me once when some Dawn was on the dishes before they went in the dishwasher).
Don't do that. If you are out of dishwashing powder and can't run to the store but must run the dishwasher, put some baking powder in it and turn it on the hottest wash.