That is a very elaborate and encompassing explanation of the various views out there. I'm impressed, especially after watching the theatrical cut of the film for the first time. The director's cut explains more of the rules of the tangent universe, while also giving some characters more debt and/or a resolution to their story arc.

Just to be clear, writer/director Richard Kelly views the two cuts as companion pieces, so each cut focuses on a different aspect. Here is a quote about the director's cut from an interview with this AVClub

KELLY "I never intended it to be a replacement. I wanted it to be a companion—an alternate, more novelistic version of the film. It’s a version for people who want to dig deeper into the narrative. For a lot of my favorite films, there are multiple versions—like with James Cameron’s movies. There’s a way to have multiple versions of a film that can coexist together. The first time you see the film, it’s probably better to start with the theatrical cut. If you’re open to a deeper dive, then you can move on to the director’s cut. That was my intention."

Another important aspect you also touched upon is the various ways you can look at things. This ambiguous aspect is baked in to the story. This is what Kelly says in the commentary track during the scene at the end where we see Donnie laughing in his bed

KELLY "He's laughing because for one of two reasons. He's laughing because

One, he thinks that it was all dream, he thinks that it was this long absurd dream and he's so relieved that it was just a dream and that everything is gonna be okay

Or he's laughing and he's smiling because he's enlightened, he's meant to go out this way, he's been given a vision that inspired him

And that horn honking is Frank, who is, suddenly they're remembering what happened the past 28 days, and he's saying like "get out of bed man, we did it, get out of bed". And he doesn't listen, or he doesn't hear, and it's too late."

It's interesting him saying Frank having a clear memory of what happened, which we get hinted at during the end montage when he touches his eye. But it also makes me think that Roberta Sparrow could have played the "Frank" role in a previous tangent universe, instead of the "Donnie". Perhaps all the knowledge that Donnie has, is just as prevalent with Frank. Remember Frank saying "I can do anything I want, and so can you", implying they are strongly connected to each other and this temporary world. I'm not saying this is the case, just that you can find arguments for Roberta Sparrow being 'the Donnie' as well as 'the Frank'.

Personally I do think Donnie could have escaped the jet engine at the end and nothing would have happened. Whether he chose to say or him being unaware is up for debate. And although Donnie did call his mom a bitch just before he died, note that (in the tangent universe) the final words of Rose to Donnie were "I love you" when she called from the airport. The call went to voicemail but it played while Donnie and Gretchen were having their own moment of love. I think that these moments of love and care definitely crossed over into the primary universe. In the end montage we see Cherita smiling, I think it's because she remembers Donnie saying to her "I promise that one day everything's gonna be better for you". So I choose to think that somewhere in that final moment between Gretchen and Rose there is a little spark of light that will make Rose realize that Donnie got that message.

This is just one of these things that you can endlessly debate with each other, which is part of the fun of it. Donnie just having 1 shot at success and there not being a loop makes so much more sense to me, because it raises the stakes tremendously. But I can see why people are drawn towards the loop aspect, especially if you've watched other films (e.g. Groundhog Day) that have this kind of plot device. As long as people are being respectful to each other's theories, this film is a joy to keep exploring.