No; good question because this is a common misconception! Baking powder does have baking soda mixed in it, but it also has a powdered acid, such as cornstarch or cream...
You can, but yogurt tends to separate when mixed with other ingredients. You should probably just make enough for one use at a time. If you have extra, let someone...
It has cleaning and deodorizing properties. People often keep an open box in the fridge to limit odors, or you can sprinkle it on your carpet and then vacuum it...
