Dan, There are a lot of moving pieces in your question and a variety of ways to implement them depending on your needs and particular website set up. Fortunately there are lots of educators playing around in these spaces already who are experimenting with various means and methods as well as some of their short and long term implications.
I suspect some of the most interesting parts may be more closed off to you (or possibly more difficult) because in your particular case it looks like you’re being hosted on WordPress.com rather than self-hosting your own site directly. For the richest experience you’d ideally like to be able to install some of the IndieWeb for WordPress plugins like Webmentions, Semantic Linkbacks, Post Kinds, and potentially others. This can be done on WordPress.com, but typically involves a higher level of paid account for the most flexibility.
For crossposting your content to micro.blog, that portion is fairly simple as you can decide on any variety of post formats (standard, aside, status, images, etc.), post kinds, categories, or even tags and translate those pieces into RSS feeds your WordPress installation is already creating (most often just by adding /feed/ to the end of common URLs for these items). Then you can plug those particular feeds into your micro.blog account and you’re good to go for feeding content out easily without any additional work. Personally I’m using the Post Kinds plugin to create a finer-grained set of content so that I can better pick and choose what gets syndicated out to other sites.
From within micro.blog, on your accounts tab you can enter any number of incoming feeds to your account. Here’s a list of some of the feeds (from two of my websites one using WordPress and the other using Known) that are going to my account there:
As a small example, if you were using the status post format on your site, you should be able to add
https://dancohen.org/type/status/feed/ to your feed list on micro.blog and then only those status updates would feed across to the micro.blog community.
I also bookmarked a useful meta-post a few weeks back that has a nice section on using micro.blog with WordPress. And there are also many nice resources on the IndieWeb wiki for micro.blog and how people are integrating it into their workflows.
For crossposting to Twitter there are a multitude of options depending on your need as well as your expertise and patience to set things up and the control you’d like to have over how your Tweets display.
Since micro.blog supports the Webmention protocol, if your site also has Webmentions set up, you can get responses to your crossposts to micro.blog to show up back on your site as native (moderate-able) comments. You can do much the same thing with Twitter and use your website as a Twitter “client” to post to Twitter as well as have the replies and responses from Twitter come back to your posts using webmention in conjunction with the brid.gy website.
I’ve been playing around in these areas for quite a while and am happy to help point you to particular resources depending on your level of ability/need. If you (or anyone else in the thread as well) would like, we can also arrange a conference call/Google hangout (I’m based in Los Angeles) and walk through the steps one at a time to get you set up if you like (gratis, naturally). Besides, it’s probably the least I could do to pay you back for a small fraction of your work on things like PressForward, Zotero, and DPLA that I’ve gotten so much value out of.
Because of the power of these methods and their applicability to education, there are an ever-growing number of us working on the issue/question of scaling this up to spread across larger classrooms and even institutions. I’m sure you saw Greg McVerry’s reply about some upcoming potential events (as well as how he’s receiving comments back from Twitter via webmention, if you scroll down that page). I hope you might join us all. The next big event is the IndieWeb Summit in Portland at the end of June. If you’re not able to make it in person, there should be some useful ways to attend big portions remotely via video as well as live chat, which is actually active 24/7/365.
As is sometimes said: I have made this longer than usual because I have not had time to make it shorter. At least I wasn’t hampered by Twitter’s character constraints by posting it on my own site first.