RCV is a fantastic idea, but it is very difficult to get it installed on a large scale. Only one state has tried (Maine) but their state Constitution as currently worded seems to disallow it (as their Supreme Court has warned them). So for many states you'd first have to amend the Constitution to allow for RCV (or go for broke and try to get RCV enshrined in your Constitution) and then hope that those who benefited from the previous First-Past-the-Post systems will act against their interest to implement it by law or will refrain from enacting laws to overturn a citizen's referendum (which is my home state of Utah's preferred way of invalidating all citizen referendum). That said, while it's not a perfect solution it leans so heavily towards resolving many existing issues that I've long decided that if any politician publicly supports it as part of their campaign they'll have my vote.
Progressive Democrats and Never Trump Republicans need to vacate their respective parties. No idea how you and I could effect that change though -- awkward thing about "democracy", we only get the choices presented to us by those in power.
My vote is held hostage by the Democratic party. I'm reluctant to expound upon that because that will invite a partisan pile-on and I've had enough of that here.
The US electoral system (or at least the common one; one or two states have flirted with modernising it) makes more than two parties unviable. In general countries without proportional representation or similar are two party systems (or occasionally 2.5 party systems like the UK, for historical reasons), countries with PR are multiparty.
Yeah that would be a great start. Sorry state of affairs in Canada and the US is that even when politicians run on a platform of election reform, they change their tune because the system worked for them. The excuse I hear most often is some form of the electorate being too stupid to navigate such a complicated system.
The _fairest_ PR systems actually are very complicated, which is why they're rarely used in practice. Systems like PR-STV, though, are both a lot fairer than first past the post, and relatively understandable (in countries that use them, most people understand the basic mechanics, and _everyone_ understands them well enough to use them correctly, even if the subtleties are lost on most people).