MacroEconomics ...Comparative and absolute advantage, opportunity costs

Country  Bushels of Grapes    Computers

Italy           100                         300

Canada       150                         600

Using this scenario, can you explain to me...

Who should specialize and in what?
Who has an absolute advantage and in what?
Who has a comparative advantage and in what?
What is the opportunity cost for Italy if they only produce 1 bushel of grapes? What about 1 computer?
How could we get the greatest output of both?