Too much oil will make the cake batter greasy and slippery and too thin / runny. It will cause large probelms while baking, as the cake may not set up before it burns from being baked for too long. To counteract this, you can try to skim some of the excess oil out with a spoon or mop it up with a paper towel. You can also add some more dry ingreients, like flour or cocoa powder. Also try to add more amounts of the other ingredients to even it out.
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
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
Cake Batter Is Changed Into A Physical Change
To mix cake batter?
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.
You will get really fat and sick... yuck!