Overall, Trigun Stampede adheres closely to the manga. Some minor details might differ for the sake of the adaptation's flow and visual presentation, but the core remains the same.
It's quite accurate. The anime version of Trigun Stampede mostly adheres to the manga, with just a few minor differences that don't significantly impact the main plot or character development.
I think it does to a large extent. There might be some minor tweaks here and there, but the core plot and characters are pretty much in line with the manga.
Trigun Stampede takes some liberties compared to the manga. It changes certain story elements and character traits to offer a fresh perspective, but this might not please all manga purists.
Well, the themes of Trigun Stampede Original Story include survival. Given the unforgiving environment they are in, characters are always fighting to survive. There's also the theme of friendship. For example, the relationship between Vash and his companions is important. They support each other in different situations. And the theme of good vs. evil is present. Vash represents good, and there are various antagonists that represent different forms of evil in the story.