Unless your personal auto insurance provides coverage outside North America, the distinction between secondary and primary collapses for international rentals. However, most cards exclude rentals in some countries, and we should pay attention to those restrictions.

Transferring points from American Express, CapitalOne, Chase, Citi, or Diners Club offers the potential for a much higher financial return than using the booking portals provided by those same programs. There is a tradeoff of complexity for value, but if your objective in intercontinental premium class flights it's unrealistic for most people to book through a points portal.