I did my best at sewing the rails in the opposite directions. The curve is noticeable to me on only a few blocks and its the last strip, the ends are a little bit longer than the middle. Does that make sense?
I'd like to clarify pressing, ironing and setting. Pressing is lifting the iron vertically up and down and placing it on the fabric. You don't want to move the iron back and forth like you would when you are ironing a shirt, correct? To set the seams it is right sides together and press the hot iron onto the stitching line.