Thanks for a meaningful comment, I'm glad you like the article!
Nice thought experiment. Let me try to answer question by question.
The train example is more complex than it seems on the first thought, I really like it. : )
Yes, 5 lives are usually more valuable then 1, but: those 5 men are working on a part of the railway where a train is scheduled to pass by (I suppose), while that 1 isn't. So, it could be their mistake, or the mistake of someone who was planning their work schedule. Hell, I could even end up in jail if I would pull the lever and change the direction of the train to a non-planned direction, killing a man in the process! Thus, if I had enough time to think, I would probably not pull the lever. But, what if it was 100 vs 1, or 1000 vs 1, or whole human race except me and the 1 vs the 1...
Now let's focus on quality over quantity. It's impossible to accurately calculate, but if I would be able to choose without any legal consequences, I would try to save the life/lives that has/have the most total potential for enjoyment and positive impact on the world. : )
As per the bridge twist, I think that the difference is in the fact that it's harder to do something bad to someone more directly than more indirectly (pulling the lever while alone in a train cabin vs looking in the eyes and pushing off the bridge).
It's easy to estimate human value in very clear situations such as the ones that I provided in the article, but in reality the vast majority of the situations are probably much closer to your examples.