On the sour.......remember that sourdough culture is a combination of two living things. Yeast and bacteria. With "established" heritage type starters.....those that are handed down from generation to generation....the uniques ones like the San Francisco types, the yeast and bacteria form a symbiotic relationship. One depends on the other. One feeds and protects the other. Those are stable and predictable. The yeasts feed on sugars and emit carbon dioxide for the leavening (and alcohol...aka "Hooch"). The bacteria break down the starches in the flour to fermentable sugars for the yeasts, and in the process, generate lactic and acetic acids, which taste sour. If your bread is sour, you have a culture, or manage your culture in a way that benefits bacteria, or have weak yeast. Most folks that like sourdough like it for the sour flavor. If not for that, you can use commercial yeast, which has no flavor.
On starters, finding or creating a starter on your own that has those established "scratch my back" relationships is rare. You can get a mix of bacteria and yeast going that will leaven bread and taste sour, but it's not likely it will turn out like the ages old ones. If you want to save yourself a lot of trouble and truly find out what a good sourdough is, get an established starter like Carl's, the KA version, one from Bassman or one from a variety of other commercial sources (look carefully and you will notice that some of these "heritage" starters they are selling are actually ones that have been created recently by individuals....they are not centuries old......so it can be done).
Here are a few:http://www.northwestsourdough.com/ne...terlaunch.htmlhttp://sourdo.com/http://www.breadtopia.com/
Spend some time on these sites and you will find that things are done different......no right or wrong.....just different. But they usually revolve around three key factors.
1. Sourdough is a culture of flour and water only that contains the living organisms of yeast and bacteria. At the preferred temperature of 65 to 85 *F, they grow quickly, so in these temp ranges have to be fed often (12 hours or so). At refrigerator temps, they go into hibernation and will stay healthy for weeks if not months.
2. The ratio of water to flour is referred to as "hydration" and is expressed as a percentage of content relative to the weight of flour, usually by weight. Equal weights of flour and water is 100%. Equal volumes of water and flour are around 165% (a thin, runny starter). Both work as would one that has half as much water as flour, by weight (50%). Where it matters is that the ideal percentage of water (by weight) in the bread dough is around 38% to 40%, so the recipe you use (amount of starter) has to be adjusted to the percent of water in your dough. Not hard, just have to adjust for it. This is made harder by the fact that a "cup" of flour can vary a lot by weight. Packed vs. loose or sifted for example. Best results are obtained when you weigh ingredients, but a lot of folks measure and it will work.
3. True sourdoughs are only fed water and flour. No sugar, no commercial yeasts. Established starters will go to town on flour and water alone. A lot of sourdough breads are nothing but flour, water and salt. The yeasts and bacteria in the culture take it from there and do all the work to produce the breads.
Caution: This can be addictive!