Listing 1: Sample Query That Demonstrates Different I/O Results [goes with Q1]
SELECT FirstName, LastName, TotCost
FROM dbo.Employees e
  INNER JOIN (
    SELECT e.EmployeeID, SUM(UnitPrice * Quantity) TotCost
    FROM Employees e
    INNER JOIN dbo.Orders o ON e.EmployeeID = o.EmployeeID
    INNER JOIN dbo.[Order Details] od ON o.OrderID = od.OrderID
    GROUP BY e.EmployeeID) a ON a.EmployeeID = e.EmployeeID
ORDER BY TotCost DESC