Thanks, James, for those hints! This is a fun thing to do! Well, I started with a quart, but am scaling back quickly. A pint is probably about right. It is fermenting quickly in this warmer weather, and I can probably use fewer grains because of that too.
I'll try the distilled water "rest" for some - I wanted to keep a back-up culture of the grains and that sounds very simple. That's a great suggestion I hadn't come across yet.
The kefir bread thread was really interesting too. I am guessing that I can also substitute for buttermilk in almost any recipe (being another cultured product, it seems very similar to me in consistency and taste).