From what I've gathered so far if Site A and B is connected with a point to point leased line these sites would need to add another line in order to access the Internet. Basically the point to point line can't be used for Internet is that correct?

Let's say a company has 5 locations. A typical setup would be to have Internet at the main site and funnel rest of the sites to the main office using a default route. Does that sound right?