How does the Pardoner keep up his extravagant lifestyle? The Pope gives him money to spend
His church pays for all his expenses
He tells stories to make people buy pardons

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).