Which format is more useful single step income statement or multistep income statement? explain

Usually assets are reported at historical cost. But does knowledge of its market value ever useful? Discuss

When a company pays to buy equipment immediately is recorded as an asset but the payment for salaries or any other expense is classified under the expenses, In both cases the company pays cash but in the first case an asset is recorded and an expense is recorded in the second case. Why? Explain the difference between assets and expenses.