Welcome to the Lithosphere, Mark. 🙂
The good news is that we try to make our software instances fairly SEO friendly. For example, you'll note that our URLs in a thread are canonical (and describing the subject) rather than a bunch of query string parameters.
In the page markup you'll also note that we use a lot of rel=nofollow tags around links that people post in their messages. That way, the spiders dont see messages as just a bunch of link-farming initiatives. Conversely, we have a toggle in our blogs so that a trusted blog author does not have the rel=nofollow tag applies to the links that he or she provides in their article (because a blog author's links are considered trustworthy).
You can read more about our SEO approach here:
http://lithosphere.lithium.com/t5/Growing-Successful-Communities/Understanding-SEO-Friendly-URLs/ta-p/6560
and learn more about what we recommend here:
https://community.khoros.com/t5/Search-tools/Optimizing-your-page-preview-for-SEO/ta-p/309293
But going a bit deeper into your questions, there are some limitations as well as possibilities with what you're asking about:
1. We can host a static sitemap for you without any problems, but the application cannot generate a dynamic one for you.
2. The REST API call that would extract a list of threads for posts made in the last 24 hours would be one from the Community Class and the threads/recent Method. The arguments that you can use are for how many pages are listed though, and not by date or time. Through some coding (and perhaps making a couple of calls), you can arrive at this list.
Hope all of this info helps.
