Certainly, white all purpose flour will work in muffins. Although they might turn out to be cupcakes, rather than muffins.
Use the all-purpose flour. Expect a different taste, and, possibly, texture/consistency.
yes
yes
Generally you can, yes.
yes. They are the same thing. Plain flour is an Australian term where all-purpose is the American.
NO, baking mix usually has baking powder or baking soda in it and sometimes milk solids plus flour of coarse.
the best flour to use would be all-purpose flour.
Sapin Sapin is a glutinous rice and coconut dessert, traditionally calling for rice flour. If your recipe calls for all-purpose flour, you can safely substitute equal parts brown or white rice flour.
Yes, self-raising flour will help make the muffins rise, while plain flour won't unless you add baking powder to the muffins.
Muffins can be made with white flour, unbleached white flour, whole wheat pastry flour, spelt flour, or a combination of several types of flour. Muffins can be made with self-rising flour if the amount of baking powder, soda, and salt in the recipe is adjusted.
Plain flour most likely is AP flour and I say yes at any rate.
Not to bake stuff like bread. You can substitute 1 baking soda for 2 baking flour to make reductions. You can substitute 1 baking soda for 1 baking flour for gags (throwing on someone in the shower).
You can sometimes substitute all-purpose flour for whole wheat flour in a recipe. To do this, you would use the same amount. However, not all recipes will turn out if you do this.