YEs you can
Use wholemeal flour instead of white - OR - replace some of the white flour with bran.
"White flour" is wheat flour, it's just been processed in a slightly different way. It's perfectly fine to use whole wheat flour instead of white flour in a pizza crust.
Yes, assuming that by "plain flour" you mean all-purpose flour. Because all three sound like the exact same thing.
Teff can be used as a substitute for wheat. If you are making injera bread but teff flour is not available, you can use wheat flour, rice flour, or barley flour.
Yes, you can.
No, because the shortbread will rise. You can use plain flour or rice flour instead though. it would be really nice.
You can use plain flour with a teaspoon of baking powder.
Yes, you can use Bisquick as a substitute for flour in this recipe.
Don't quote me on it, but I think it's healthier...
Corn flour is quite different to regular flour and most recipies will fail if you use the wrong type of flour.
Regular bleached white flour.
Yes you can, I use whatever flour I have to hand.