Yes canola oil is a type of vegetable oil, there is a slight taste difference but your not likely to notice that in the final product.
You can, but canola oil works the best.
yes
Yes you can.
To replace one cup of margarine one may use 1 cup shortening plus 1/2 teaspoon salt OR 1 cup butter OR 7/8 cup vegetable oil plus 1/2 teaspoon salt OR 7/8 cup lard plus 1/2 teaspoon salt.