Oil makes the cake more moist and dense. Otherwise, it would be a drier, fluffier cake.
The oil is what holds all the ingredients together.
to make it have it's flour so it can have a nice texture
you don't always need this, sometimes margarine or butter could be used instead.
Texture, moistness
No but you can make American muffens with vegetable oil
Rice is a vegetable. In a cake mix, oil is oil. Some oils have a stronger flavor than others and this may come through in the finished cake, but as far as texture or performance, any oil will work.
No.
Yes
vegetable oil or butter
you can, but the results may not be exactly the same.
Yes, in some cake recipes, canola oil can be substituted for shortening.
Yes, the two are interchangeable. However, oil usually results in a moister texture to the finished cake.
yes.
Well, Canola oil is vegetable oil, but it will work just fine for the cake.
yes
Butter is always good.