I think you would have enough yarn if you use a larger needle, maybe an 11 or 13 instead of the size 10/6mm; you'll need less stitches and that makes the yarn go further, and you don't need one that's 60" long, a 32" or so will work just fine. Yeah, do 1 and 3 with opposite stitches and also follow the row from the end of it to the beginning.
She doesn't say to double it - that would be if you want to knit it flat, you make 2 pieces. As written, the 256 sts (128 twice) would be 73" around. If you don't want it that large, figure out how big you want it (50" would be big enough to twist it around twice) and multiply that times your sts per inch on the larger needles, then adjust so you get a stitch count that's a multiple of 7 plus 2 sts.
sue- knitting heretic