Regarding placement. My favorite appliqué method is back-basting appliqué. The pattern or placement is marked on the back of the background fabric. (Note the pattern will then be reversed.). There are tutorials on YouTube. Placement is very accurate. I also use needle turn.
One other suggestion. Think about using your pigma pen to embellish leaves on block one and flower petals on two. A pen was used on the illustration from the book. See the comparison. ——— Your appliqué stitching is outstanding and I congratulate you on choosing to do this project. I will certainly follow your progress.