The cake will not taste right (it will be too sweet) and the batter will be the wrong consistency. It will either be too liquidy (fine sugar) or too coarse and thick (coarse grain sugar or lump sugar).
It will be runny. If you don't wish to throw it out, you must compensate by adding more of your other ingredients, ie flour, salt, yeast etc and make a larger dough. Unused dough can be 'retarded', meaning placed in a very cold fridge to slow the rising and used the next day.
when you bake the cake it will be very moist (or if TO much water) soggy.
Depending on how much extra, the cake may rise too quickly and then fall. If it does turn out, it may have a metallic taste.
This will probably make the batter very gooey and wet. To counter this, you can try to strain out some of the water, or add a little more flour to thicken it up a bit more.
You will get really fat and sick... yuck!
you put about 1/2 of cake batter
If you are using a 2" deep cake pan you would need 13.5 cups of batter.
As much as you want except if your pregnant
The mixture would get stuck together and get hard glops.
10 Pieces .
1/2 full
6 cups for one layer
It depends on how deep the cake pan is.
5 because the cake swells when it bakes so 5 is enough
It depends on how much of a blueberry flavor you want. For the average amount of cake batter, add about 1 to 1.5 teaspoons of extract.
Yes. Over-mixing the batter can deflate air bubbles. It can also create heat, altering the way the ingredients are an how they will then react to more heat in the oven. This can result in a flat, dry, or dense cake. If you whip the batter too much, and air gets added in, the cake will then rise and either be light and fluffy or will pop.