Answer:
A. By becoming a corporation and selling its stock.
B. These trades are handled through a stock exchange, with a broker representing each investor.
Hope this helps a bit.
It depend on whose in charge in the government.
The reason would be that if they borrow money, they also have to give this money back someday while if they just raise taxes, they basically will get the same money by taxing their population and won't have to return anything. It is true, however, that the people will be taxed more and that they will have to pay the price that the nation would otherwise pay.