So it is basically, because you’re using tailwind anyway for styling, using it for layout is nice for consistency sake. I get that.
For (2) however I usually use CSS custom properties to reach for preset values, e.g. setting "column gap" to "var(--margin-inline-wide)", and "row-gap" to "var(--margin-block-short)" etc.
That's fair. If the question is "would I use Tailwind primarily for layouts and little else" then the answer would be "no". I would definitely use CSS variables along with grid or flexbox, because its essentially the same end with less complexity.
I would also point out that Tailwind only makes sense to me when I'm also breaking up each individual UI element like cards or buttons into reusable components, either using a reactive framework like React or Vue, or a server-side template system. I'm not sure the maintainability of Tailwind survives with more monolithic HTML pages.
For (2) however I usually use CSS custom properties to reach for preset values, e.g. setting "column gap" to "var(--margin-inline-wide)", and "row-gap" to "var(--margin-block-short)" etc.