My first question: I have looked at various websites and guides to sewing with Japanese patterns, and they all say that such patterns do not include seam allowance, including GosuRori. They also say that the patterns will have a number stating how much allowance to add. However, when I looked at my patterns, there was no indication of the allowance I needed to add, and it appears to already have seam allowance, and indication of a (supposed) stitching line. Like this-

Second question: I have translated and translated this to my wits end, and this is probably a basic sewing technique, so I do apologize. I translated the steps to this pattern with every guide I could possibly find, and I'm hoping that someone could clarify this one step. I am making a bustle skirt (a pattern for the IW one here: http://www.lolibrary.org/apparel/classical-skirt) and I need to install a zipper. In steps 2(where I sew the overbustle) and 8(where I sew two of the underskirt panels), I am told to press open my seam allowances (understood). But then, the instructions say "左のみファスナー開きをあけておく", which keeps translating to "Open the left zipper only"? I know that when installing a zipper, you put it in the seam allowance, and the steps don't tell me to actually sew in the zipper until step 9. So, what is it telling me? To rip open the seam allowance now (er, at steps 2 and 8)? To not sew the left seams at all? I'm so confused!
Finally, the skirt appears to be a half-elastic waistband (more of a 1/3rd with my measurements), does that seem to be correct?
Sorry for any trouble, and thank you for any help I get! <3