Under which circumstance is a company the most profitable? (Theoretically speaking)
When the marginal cost of production and the marginal revenue of that company's output (product or service) are equal.
After which year did religion stop being an important factor in the politics of Europe?
After 1648, and the end of the Thirty Years War.
Which particular change in fiscal policy is responsible for Ireland's rapid growth in the last decade when compared to the rest of Europe?
The halving of the profit tax. It has attracted businesses and investments looking for greater profits.