V321 is certainly more intuitive in the ratings (it's basically an upvote/downvote system) if not the counting, but it's still quite strategic. On the plus side, the most basic strategy of simply upvoting who you want to win and downvoting the candidates you hate ensures the most divisive candidates are removed from the pool and the obscure fringe candidates are unlikely to benefit, but there's a fair bit of juggling how many candidates to upvote or downvote depending on what you think of the candidates seen as most likely to win the final round
That is an implementation issue. IRV can be implemented as either requiring complete ordering or allow partial ordering (you have n candidates, you can assign each one level 1..n, but you may use the same level for more candidates to describe partial ordering).
Technically, that’s a complete ordering with unforced preferences, not a partial ordering.
A ballot with a partial ordering would be won for which for some pair of candidates A, B, none of A> B, A<B, nor A=B would be true. Equal preference and absence of preference are different.
A ballot that worked this way would be a meaningful extension in existing ranked preference methods that aggregate pairwise preferences from individual ballots, lile ranked pairs. (Whether the effect would be desirable is not something I’ve really analyzed, but that kind of method would naturally make distinct use of the information.)
Yes, it is weak ordering, not partial ordering.
> Equal preference and absence of preference are different.
Well, it may be understood as absence of preference, provided the absence of preference is transitive.
Framing is important, and I think STAR would be most optimal with good ol' Likert scale (five or seven point) rather than 0-N stars. But I think even simpler is the "3-point Likert" behavior of V321: approve, disapprove, and "meh, ok."
I don't like how IRV forces me to rank candidates I may know little to nothing about (e.g. downballot randos not on "my team"). I don't really care if Kick Puppies Party is above or below Trip Grandparents Party.