> All US ambassadorships are political appointment, therefore option 2 is the only answer. These positions are almost always ceremonial. They are there to execute the will of the president.

Not really, a foreign service officer can be appointed by a president to be an ambassador. A recent example from the news is Marie Yovanovitch. In regular times, my impression was that foreign service officers were appointed to the more difficult and critical ambassadorships (e.g. Ambassador to the USSR), and friends of the president were appointed to "easy" ambassadorships (e.g. to a staunch ally with a fashionable capital).