Praetor said:
Two, do all officers in real-world navies make captain?
A great question and one that I've also raised. I think a lot of people are mistakenly assuming that if one hangs around long enough that he or she will eventually earn captain's stripes/pips. Not the case. The military is a merit based organization. The idea that someone gets a command of his own because he's managed to stay in the service for thirty years is ridiculous.
And what did Chekov really show during the TOS series or films that warranted his being placed in the captain's chair? Of everyone on Kirk's crew, he was the person who's most remembered for his stupidity and his knack for finding himself in the middle of bad situations (some his fault, some not) that ended with people getting hurt or killed. Is that someone you'd want leading hundreds of other men and women?
Kirk's path to captaincy isn't clear, but he clearly deserved the role. Spock didn't desire command, but he had leadership qualities of his own that made him an asset to his crew (officers and cadets alike). Scotty was captain of engineering, a rank that wasn't intended for command but to note his expertise in his field. Did he deserve it? Absolutely. Sulu's career started much like Chekov's. But he grew into a leader and became more assertive as time passed. By TUC, he clearly belonged in the center seat.
--Sran