Good morning!!!
First fusible webbing: Steam a Seam works just fine, although it's not so good for printing onto the backing paper as the ink smears right off. Also be sure that you print/mark the applique shapes onto the backing paper that will stay on the fusible webbing after it has been applied to your applique fabric (since there is backing paper on both "sides" of the fusible webbing). My favorite fusible webbing is Shades Softfuse. Heat N Bond Lite or Featherweight is also good.
To blanket stitch the points: If you use the 2.4mm width and stitch length this is what I do... start at the bottom of the point (i.e. the wide end) and blanket stitch up the side. When you get to the top, there will be a place at which the leg of the blanket stitch falls onto the other side of the point - you'll be really close to the top. When you get to this point, do some straight stitches (2 at the most) up the edge right to the point. Now do a blanket stitch with the leg pointing straight down the middle of the point and then follow it with 2 single stitches along the edge - you'll be going down the other side now. Then continue blanket stitching as normal. You may have a couple of blanket stitches on each side of the point where the "legs" are crossing. Hopefully this pic will help - and it will look a lot better in thread!!! There's no need to mess with the stitch length!