It's hard to not start a starter with yeast and can be dangerous to not use a commercial yeast to keep a starter going. If the conditions are not right or it's

It's hard to not start a starter with yeast and can be dangerous to not use a commercial yeast to keep a starter going. If the conditions are not right or it's not a safe yeast colonizing your starter it can be deadly. I don't have a strong opinion about the origin of the starter. It will definitely influence the flavor of the bread but other than that I don't think the origin is important. More important is the rise times. A longer rise is more likely to convert more sugars and also more likely to give indicators of a bad batch.