First off, I'd put that shortcode on a page rather than on a post. The page itself will become part of your navigation menu. I don't think I was clear about that.
The posts themselves (the ones you list with the shortcode) will get mixed in with the other posts on your home page, but they will still be "specially linked to" on that page in your navigation. If that page with the shortcode is the parent it should display all the custom excerpts for your category / categories. That would include your introduction to the topic. But now I'm now wondering if you might need to add a second shortcode to keep the introduction on top? That shouldn't be difficult.
Whatever you do, don't change the date on any post. That will lead to 404 errors on search engines. The date is a permanent part of the URL of each post so changing it will mean the post won't be there where it was (if this makes sense?). Don't change URLs because when Google indexes them, the old link will be gone and the new link won't yet be visible.
I'd say go ahead and publish what you are working on. Then I (or another volunteer) can see what you are doing. It's much easier to see something concrete than to go by speculation.
Or how would you feel about setting up a second blog to use for testing how this will work. You can do that for free, use the same theme, even export/import your real blog to the test blog. Set its privacy setting to not be indexed by search engines but still public. Then you can make mistakes, experiment, play, and allow us volunteers to see it, help with the set up. I have a bunch of test blogs myself just for that purpose, and it makes me feel free to experiment with things "behind the scenes" and learn a lot. I understand if that sounds difficult, but it has been a great way for me to use wp.com.
BTW, you are not "pushing your luck." As I said, I enjoy interesting questions. This is interesting.