Thanks for taking the time to write out such detailed information! A few thoughts:

• Twitter links are, in my understanding, like friend links. If you aren’t a Medium member, you can read without hitting the paywall. But if you are a logged-in Medium member, your claps will still be counted and go to that author’s earnings. Which is exactly what you want on Twitter, because most of your audience won’t be Medium members.
• You are right about linking to facts, and Medium explicitly prefers this to footnotes.
• Some of the different topics/tags on Medium are like different subcultures. People read and clap much differently on articles in Writing than they do on for articles in Science, for example. (Writers in general are more likely to give more claps at a time, because they know the esteem-boosting power of a high clap count — even if it’s not actually as important as the fan count.) I suspect that how articles are evaluated for curation also varies among topics.
• Under the content section, you warn us not to republish a previously published Medium article. I was under the impression (which could be wrong) that Medium allows this as long as you delete the original article.