Depends on the recipe. As long as it is cool it should be all right. Some things you could use it as long as it is spreadable, warm room temperature. Using butter instead of oil will give the finished product a very slightly heavier texture, but for most things it shouldn't matter.
If a frosting recipe has butter in it, use the butter. Oil will change the consistency and not taste good.
In most cake recipes, the butter is creamed and blended with the sugar. Melted butter has different mixing qualities and would change the consistency of the batter. Melted butter should not be used unless specifically called for in the recipe.
No.
By changing the frquency recipe of the soudn
Yes, but it will change the taste slightly.
Shortening or lard could be substituted without any major change in the recipe.
Icing made with butter as the fat product. Here is the recipe I use: 1 pound powdered sugar 1/2 cup butter 1 tsp Vanilla Cream together. Add 1 Tablespoon of milk at a time until desired consistency.
It gives a different texture since it is hard from being cold. Room temp. is easier to melt and give a different consistency.
Peanut butter cookie recipes are easy to find. They can sometimes be found on the peanut butter jar label. Many cookbooks will have the recipe, as will recipe websites such as All Recipes.
Meringue cookies are butter and oil free. See link below for recipe.
Changing things is almost a rule for good cooking. Just as the taste of food will change by season, you'll want to adapt a recipe to your taste.
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.