I did one (by hand) via English Paper Piecing. I just checked my templates and the individual pieces were 2.5" finished. If I remember correctly, I just cut 3" strips and then cut the individual pieces using the 60 degree line on my ruler. A bit of straightening along the way but it was pretty easy cutting all in all.
When I'm calculating yardage for something like this, I simply figure out total square inches for the quilt and go from there. If you're only using 3 fabrics (as I did in the one I made) it would be fairly easy to figure out - get your total square inches for the quilt and divide by 3 for the total number of yards/fabric that you need. I always buy a bit extra for safety's sake AFTER I have the math-whiz DH check my numbers!