@ElsieDKAF used those measurements by volume. I used those too until last month when I visited more recent sites to get some different recipes. They say to use equal parts by weight and those measures by volume are fairly equal by weight. ( I don't imagine a pioneer woman in a sod hut on the prairie used a scale to get weight exactly down to the gram) I like the consistency of that mix better. The flour depends on your taste. AlaMoi used buckwheat. That sounds good. I tend to use all purpose flour because it is neutral compared to others and you can use other flours in your recipe with it if you want something different.
I did use instant or rapid rise yeast but now I am trying to develop my skills to handle making more varied recipes using just the starter. In the future, if I need to make bread for an occasion and i absolutely need it done it a couple of hours, I will use the recipe with instant yeast added. I use the starter for the taste and the yeast for dependability. Come to think of it, the two new recipes I tried, used starter and used baking soda and baking powder for the levening. Isn't that more or less the same thing?