I'm actually working on that pattern now, it's been a WIP for quite some time unfortunately due to weddings and babies taking priority!!
I advise against the Fairy Frost though. The one's that I've fingered are a heavier weight fabric, and the heavier weights are not as easy to work with when sewing small pieces together and very tricky to use a heavy weight like FF with a light weight like a WOW. You'll find that your 1/4" seams will be more difficult to keep uniform.
The size of the double 9 patch block (finished) is 4.5" which means that the smallest single block is 1/2" (finished). It is strip pieced though.
I sewed dozens of 1" color/white/color strips (using different combinations of color), and white/color/white together then sub-cut each of them and kept them in mini stacks. I would then choose random pieces to make my 9 patches and kept those in stacks. I then cut my white squares and chose random 9 patches to make the double nine patch. I have all of my double nine patches done and I've been playing around with EQ7 to see if I like different block with them other than Shoo-Fly. I think used a total of 20 different colored fabrics in primary and secondary color prints, and perhaps 5 different WOW.
Good luck! Its a fun quilt!