Are there a handful of broad principles that constrain anticipation about biological systems or processes that you could highlight?

There are. My thought about the current event idea for the topics would be simply to use those as a jumping-off point to talk about the foundational aspects, since otherwise I'd feel somewhat aimless as to where to start. But the way you phrased that made me think about more about how to structure a foundations only-type post, and I think I could pull at least some of that off in a way that would be useful.... I shall continue to think on this. Thanks for the suggestion!