yes you can use one fresh stick of cinnamon in cookies
. . . . . . yes . . . . . that is what it is for . . . . Cinnamon is in apple pie, cinnamon rolls, snickerdoodle cookies, and cobblers, to mention a few.
Oatmeal cookies can be made without the flour, however the oats will need to has a binder. The binder could be ground up oats, for example. Without the binder, the cookies will fall apart and never solidify into a handheld object.
Amazon sells ground cinnamon for $3.61 by Simply Organic. The bottle holds 2.45 oz. They also sell the McCormack ground cinnamon for $10.44 that is in an 18 oz. bottle.
ground oatmeal is pretty much the stuff in the can with the quakerman
I'm not aware of any difference. Decades ago terms like "finely powdered" were standardized terms that referred to the size of pharmacist's sieve the product could pass through. Today, though, I'm not aware of any difference between "cinnamon powder" and "ground cinnamon".
Cinnamon
Yes.
medium oatmeal comes from the ground.
One cinnamon stick yields approximately 1/2 tsp. of ground cinnamon. So, 4 tsp. ground cinnamon = 8 cinnamon sticks.
Actually, that is what you should use. The brown coloring in Apple Butter does not come from ground cinnamon. It comes from cooking the apple sauce for many, many hours. My family has been making Apple Butter in a copper kettle over an open fire for many decades.
The amount of powdered cinnamon you get from a cinnamon stick is a little more than the stick itself. As cinnamon is ground, it's dry properties cause it to absorb moisture out of the air, and that causes the appearance of more ground cinnamon. You will usually get about one teaspoon of ground cinnamon from a cinnamon stick.