Yes, parchment paper prevents food from sticking and is especially helpful when baking cookies. Usually you will not need to grease the parchment paper, but I have found it is worth the time to bake what my grandmother called a "try" cookie to make sure oven temperature, size, baking time and surface prep (i.e. greasing) are optimal.
I use parchment paper all the time when I bake cookies and I have never known it to make baking time longer. I still bake the cookies at the time the recipe calls for.
Parchment paper can be found in most larger grocery stores. It is usually kept near the wax paper and foil. Just make sure you do not mix it up with wax paper, as they are not the same thing. If you don't have any luck in the grocery store near you, you can check out specialty kitchen or baking stores.
with a piece of paper
yes you can
yes and cornstarch can be in pavlovas
Parchment paper
This depends on the cookie you are baking. Some cookies are fine without parchment (like peanut butter). If you grease the cookie sheet or have a very good non-stick pan you may be alright with parchment paper. However, parchment paper is the best thing to use if you want perfect, golden cookies. A Silpat liner is also a good product for lining pans when baking.
Baking soda reacts with any acid in the other ingredients to make cookies rise.
You may use either. In both cases I recommend greasing the pan, placing the paper in, greasing the pan again and then dusting it with flour. Batter cooks more evenly, rises symmetrically and releases cleanly when done.
Parchment paper, usually hand pressed
Parchment paper
== High density paper treated with acid == Baking paper (Vegetable parchment) is made using high density paper (made from regular wood sources) that goes through an acid treatment. The result is strong, non-stick and heat-resistant. Silicone and other oil-based coatings are sometimes added to make it non-stick. It is also good for easy clean up, it is not just for baking you can use it to line a basket to put food in at parties
papyrus