1 In the U.S. macaroni is sold by the box or by the bag. However, it may be different in other parts of the world.
2 macaroni is a non-count noun. it is used for non-count nouns.
3 Verbs that follow ask are in the infinitive.
Example; I asked her to help me with algebra.
4 made is used because you have to make the pizza before you could bake it.
cook refers to all forms of using heat to prepare food.
There is no simple rule for when to use make, cook or when to name the cooking technique such as fry, boil, bake and so on.
You just have to listen to the native speakers and say what they say.
For example; I would cook dinner, make pasta, bake pizza and fry eggs.
5 oil is a non-count noun. You can use oil or some oil.
If you want to use a specific amount you would use something like a table spoon of oil, two cups of oil and so on.