Fell in love with the brown option so bought the pattern. I'd suggest laying out the blocks based on your choice, and then sew them together however you prefer. He has directions for sewing in rows, alternately pressing the seams so that when you sew the rows together, you can spin the seams. If you aren't inclined to spin the seams, then which way you press is not important.
The layout shows heavy dark lines, but it looks like those are more to help with laying out the blocks. Those dark lines don't appear to have anything to do with sewing the blocks together once you have them laid out correctly.