At this point, I can follow one of two approaches --- the first maximizes scrapiness (I suppose I could quarter ALL the charms and then chain piece them into strips of 4 to really, really get a scrappy look, but I'd like to get this project done in the next year...)
The second approach results in more similar 4-strips than the first, but there's still a lot of scrapiness and a few less seams to sew.
As for the block, here's my thinking for a 6" unfinished block unit ---- mind you, this is totally untested, but it's the direction I'm heading. The measurements listed are for the unfinished/cut-size. The "side wing" is a 3.5" square cut in half once on the diagonal; so, 1 - 3.5" square per quarter block is necessary. The strip-pieced charm units should measure 2.5x8.5" unfinished. Scrapiness aside, 1 charm square yields 1 - 6" unfinished block unit --- join 4 units together and you end up with a finished 11" square X block.