Incorrect. The optimum price is achieved at the intersection of the supply and demand curves.No, that's the equilibrium price. A business's point of profit maximization occurs when their marginal cost of production is equal to the price they get for their products.
Depends upon the definitions used but this thread is not about either "optimum price" or "equilibrium price" or "profit maximization".
It's about TAX LAW!! Never mind your red herrings.
It is such lack of precision that causes problems I have trying to avoid being too technical and it muddies things up at times.