What country does Stephen Harper own?
He doesn't own any country, but he's currently the Prime Minister of Canada.
Who was the leader before Stephen Harper?
This depends on the context. If you mean of the country Canada, the Prime Minister of Canada before Stephen Harper was Paul Martin. The leader of the Progressive Conservatives at the time of the merger with the Alliance party, led by Harper, was Peter Mackay. Harper eventually emerged as the leader of the mainstream right wing parties in Canada.
Is Stephen Harper the real prime minister of the whole Canada?
Stephen Harper really was (though it may be hard to believe?) the Prime Minister of Canada from 2006 to 2015, which is a position in the federal government. The provincial governments, however, are co-sovereign with the federal government, and each has its own Premier. So, Stephen Harper was the Prime Minister over every aspect of Canada that falls under federal jurisdiction.
How does Stephen Harper serve the country?
Stephen Harper serves the country by not being a dictator. --------- Actually the Canadian is effectively a dictator between elections. The previous Liberal governments concentrated power into the Prime Ministers Office to such a degree that even if the party did not agree the PM could take steps to ensure everyone agrees with the PM and force the house to pass bills they do not want to.