What a lovely comment, both in terms of content and format! (I'm a sucker for cleanly-written paragraphs and well-placed italics.)
To answer your first question, I've actually seen this Fast/Speed discrepency several times before, but I think your results have set a new record for incongruity - congratulations! The way this happens is that the attributes ("Fast", "Coolheaded", etc) are calculated first - they're what the answers directly affect, and they're the basis for almost* all of the other results. The presence or absence of certain attributes are used to calculate the stats, and "Fast" is certainly the most heavily-weighted attribute when calculating Speed, but it's not the only one.
*there's a few specific answers you can choose that will have a more direct impact on some of the Abilities, but they're rare.
In the case of your particular Fast/Speed mismatch, the lower Speed may be the result of lower scores in attributes like "Reckless", "Shedding", or "Routine-Based", or higher scores on stuff like "Whimsical" - there's more factors, but looking at the rest your results and the answers you suggested, those would be my most likely culprits.
Alternatively, since the stats are calculated as a percentage and always add up to a stat total of 450, it could also be that the attributes feeding into the other stats were just really strong.
As for your other question about how Abilities are chosen, the Abilities are the most direct result of the attributes - almost 1-to-1. So for instance, everyone who gets the 'Fast' attribute will get an Ability directly tied to that. In your case, you got "Swift Swim" because of your heavier Water-typing, but other possibilities could have been "Speed Boost", "Sand Rush", "Slush Rush", or "Quick Feet".
This was a total accident, but I do love that some of the Abilities can potentially explain the discrepencies between the attributes and stats, as you observed. So for instance, if I'm envisioning the Pokemon that matches the description in your results, I'm imagining something that's usually slow, but becomes lightning fast when it's raining.
I hope that answers your questions, and if not, let me know - every time I explain myself, I grow more powerful :)
And speaking of answers, thank you for the suggestions! Here's what I can do with those:
Q2: Funnily enough, I just added the largest-yet answer update (literally a few hours after you posted - rough timing!) but I think one of the new answers might cover you on this one. It's the one that goes "I maybe take a few things that look interesting, just because I like collecting cool things." It's lacking the "display" part, but would that have spoken to you as a viable answer?
Q16: I absolutely love this answer, and I love the way you wrote it! It's totally going in the next answer update, and I think I have the space to put it in your exact language.
Q28: I think this one's valid, but I might need to work it a little bit to make sure that it plays nice with the other answers and doesn't overshadow them or break the question.
Q29: Here's another one that sort of got addressed in yesterday's update, where I added "I'd organize based more on aesthetics than any functionality," except that I think yours actually has a new wrinkle with clearing stagnant energy - that's so evocative and feels different, and I think I'll probably add that one too!
Q33: And one more now-addressed answer, but this feels kind of different. The new one is "They'd all have experienced the same sanitized version of my personality," which feels like the same concept, but it feels like it has a different tone... would that answer speak to you, and if not, what would you say is missing?
I hope that response wasn't too long! I get very excited about these things. Thank you again for the suggestions, for the kind words, and for sharing your results - it always makes me happy to see what people get :)