I generally agree with most of your assessments and classifications, but: I can definitely eat a tostada with one hand (if it's crispy). To me, a taco is a folded tostada (when I worked at a mexican restaurant, we also had a bowl-shaped tostada ("salad in a bread bowl"). To me, that is a continuum. The ingredients are a bit less important (my preference is al pastor on a steamed soft corn tortilla).

The moment you "wrap" (fully enclose in a tubular way), I think it moves to a different part of the embedded space which includes all wraps (https://worldwrapps.com/). The mission-style burrito definitely has the "rice and beans inside" in addition to the primary (meat, veggie, whatever), this sounds very much like the "in Texas, chili doesn't have beans" argument.