Q. I’m trying to figure out where the pattern tells you to add the grain line... Is it the line marks along each pattern piece?
Also, do the broken lines always meant cut on the fold? I’m not sure about pattern 1122 on the side skirt.
A. The dotted lines do usually indicate cut on the fold, as well as indicating the grain-line.
In the case of the side skirt, the way that the pattern is laid out indicates that you'll want to cut two of that piece (no folds), using the broken line as your grain-line (so there is no side seam, it's all one pattern piece there).
For the front skirt, you can see that the line closest to the + is solid,
so you should cut two of those, once again with the grain-line as that solid line. For the front and back bodice, those dotted lines are both your grain-lines, and an indicator of cutting on the fold.
At this point, definitely pay attention to the illustration so see where there are and aren't seams. They can be a pretty handy guide when the pattern pieces look confusing.