For the scarf I would use the sticky stabilizer especially since you want it to look good on both sides. If you use iron on it would be hard to get the extra off when you are done. I would pick an open line design. Some of these fabrics don't do the fill very well no matter what you do. If you don't use the stick I would be tempted to use a disolve one. My mom has the feature that she can baste the outside of the design and I would use it to help keep it from moving. The disolve one would make it easier to remove it afterwards and open up some other design possibilities.