I love all this information -- we've been doing this for about a year or so - my only info to add -- some plastic containers (recycled regular laundry detergent bottles) leaked somehow -- not sure why or how - everything was sealed, but somehow the liquid got out. So we used glass jars as storage.
We call it laundry snot
I've tried the powered tutorials and found that didn't dissolve properly in the wash - and I would find a handful of soap pebbles in the dryer. I'll stick w/liquid.