Articles -- yes or no?
It seems we haven't been using them so far, and I haven't missed them...
Regarding the future and the irrealis, perhaps we could have a spectrum of certainty-- improbable, neutral, and probable. Perhaps "se" in the neutral spot, perhaps recycle "vo" as the improbable (owing to its similarity to "vi", the proposed negation-- it's "leaning toward no") and "tu" as the probable option.
These could be used in other uses of irrealis as well, for example, to say something like, "In the unlikely event that I won the lottery, I would likely spend all my money on chocolate."