Notice that the first group of three sentences are all true. Well, we don't know about the 8 a.m. flight, but it sounds as if the information is being given on good authority! All three sentences tell what will happen (result) if certain conditions are met. These are real conditions. The situation described is likely to happen.
The second group tells what might happen (result) if some unreal conditions were met. I'm not the head of school, Martin is not taller, and I don't speak Spanish. Thus, none of these outcomes (results) will materialize. The situation is considered highly unlikely or next to impossible.
The third group just speculates about what would result if past conditions had been different. These are considered unreal past conditional sentences. The situation described is a theoretical possibility but impossible in real life as it can no longer be changed.