Heyo! Always nice when a long-time lurker joins the site.
In regards to your SCP idea, I highly recommend getting the concept polished up in Ideas and Brainstorming before committing to the draft process. (I saw your sandbox—quick heads up; the "immune to other anomalies" angle has been done many times before and not lasted long on the site, so if you really want to make that work, it's a good idea to make sure your approach is solid. If you haven't looked at the humanoid writing guide yet, you should!)
So far as lore goes, consider reading some of the tales we have here—that's where the most detailed worldbuilding and character development happens. The In His Own Image series in particular is an excellent introduction to the Foundation 'verse.
Best of luck with your writing, and welcome to the site!