WhiteKnight, first, congratulations on taking on such an endeavor. I like doomer fiction (as well as other genres) as I am sure others here do too, but something that I find myself wishing for with the characters is that they not always be so perfect in their ability to handle whatever comes their way. I’d rather a combination of ability and luck so as to be a tad more realistic. None of us can do it all or are perfect human beings and we’ll all need some luck come a SHTF scenario. I’m guessing that you are already doing this by virtue that your characters are unawares of what is going on early on as the collapse unfolds. A feature in the storyline that could be interesting are characters having to make tough decisions.
As for what would be first, I’m no expert but am guessing that bank collapses or freeze-ups might come before stock collapses. That’s sort of what we saw in 2008.