The ranked voting method you’re considering here isn’t Ranked Choice Voting (RCV), it’s Borda Count
Borda Count works exactly as you say RCV works: The candidate ranked first gets 3 points, the second-ranked candidate gets two points, etc. This method is highly susceptible to strategic voting (voters can help out their preferred candidate by ranking D second instead of voting honestly) and parties can benefit enormously from running “clone” candidates.
RCV (more precisely known as Instant Runoff Voting) works as follows: Tabulation proceeds in rounds. At the start of tabulation, each ballot counts as a vote for the candidate ranked #1 on it. In each round, if a candidate has more votes than all the other candidates put together, that candidate is elected; otherwise, the candidate with the fewest votes is eliminated and their votes are transferred to the highest remaining choices on their supporters’ ballots (if possible). RCV is vulnerable to the center squeeze, so in your example it will fail to elect a pro-abortion, anti-immigration candidate.
I think what what you’re looking for is a Condorcet method; they are guaranteed to elect a “beat-all” winner if one exists and do not have the extreme strategic issues of Borda Count.
Yes. Your counterexample is an example of the Ostrogorski paradox, and there is good evidence that this accounts for a significant portion of why Democrats and Republicans fare similarly in elections despite the Democratic platform being more popular than the Republican platform on most issues.