There are, and my state would have banned those too it they’d heard about them when they were banning RCV. They weren’t making principled objections like monotonicity failures. They likely noticed that most of RCV’s loudest advocates were from the wrong party (and some of the were the wrong color too!), and figured that was a good enough reason to shut it down.

Not nationally, but because Maine uses both Instant runoff voting for presidential elections, and the Congressional district method of assigning electors, it’s mathematically possibly for Maine to split its electors 2-2. eg, the Republican wins both districts individually, while the Democrat wins statewide. Not this year though – needs a competitive 3-way race so the runoffs matter.

Party affiliation as listed on voter registration isn’t a loyalty oath either. It’s just a way of asking which primaries you want to vote in. You might as well pick a party with relevant primaries in your area whether you agree with their platform or not.

(Voter registration is public information and may affect which candidates and PACs send you mail.)

I think it’s Chaucer era.