No.
Most of the time you can, except when baking. It will be somewhat change the texture of cakes and muffins but you can still do it, but for cookies NO WAY!
margarine
use butter flavored crisco You could use margarine. http://www.ukfoodies.co.uk has a delicious cookie recipe, this recipe has butter, but you could substitute it with margarine.
Shortening or lard could be substituted without any major change in the recipe.
Substitutes for shortening are butter and margarine in sticks. Use the same amount as called for in your recipe. Keep in mind, plain shortening will NOT be as flavorful as butter or margarine. Do not use soft margarine in a tub as it contains too much water.
yes
Butter or margarine can be used instead, adding a couple of extra tablespoons per cup of shortening called for in a recipe.
In many things you can use margarine, lard, or shortening instead of butter, or a combination of any of them. I actually use 1/3 butter, 1/3 shortening, and 1/3 lard for the fat in my homemade pie crust, which gives excellent results. Just keep in mind that margarine has a higher water content than butter, so depending on what you are baking, the results may be just a little different than with butter.
If a frosting recipe has butter in it, use the butter. Oil will change the consistency and not taste good.
You can substitute olive oil for margarine by using exactly the same quantity. They are equivalent in any recipe.
I can't believe its not butter
Butter vs Margarine. Butter wins all the time. However,if something says to use butter,you can substitute it with margarine. It won't taste exactly the same..it'll only be a little different. So,anytime it says butter you can use either :)