Well I was wrong about rinsing out the washtub with vinegar. You use a double scoop (two tablespoons) of the soap with some old rags and run the machine through the entire cycle. I had a bunch of rags that I was going to wash, anyway, so right on.
First, the 5-gallon bucket is dang heavy and, unfortunately for me, the old man had already gone to bed. Bend the knees, that's my advice.
Anyway, my first impressions are good -- they give you a tablespoon scoop taped to the top of the bucket -- the bucket is type 2 plastic so entirely recyclable.
Update: I've used Charlie's soap for 3 loads and it is working very nicely. It essentially works like the petroleum-based detergents I've been using up until now, so at least it's not under-performing. The laundry also smells fresh, like it's been line-dried. I'm so going to miss that sharp, weird, synthetic flower smell but I have to get beyond that.
Here's a link to the babysashanmom blog that has lots of good information and links -- mostly pertaining to washing diapers with Charlie's soap, but all of the information is directly relative to other clothing.