Okay, I don't have a DD, but Obitsu share some similarities so...
Soft pastels should be chalk pastels, unless Walmart is crazy and puts oil in soft pastels.
I use white poster tack to keep my boys' eyes in. No problems with staining with the white, or weird leaching like Sculpy.
You might want to check at your local hobby/miniature stores, they might carry Mr. Hobby products, but generally you gotta order online. I use Volks' ZM spray on my Obitsu (and resins, hee) I've heard one person say they used Testor's successfully on a vinyl doll, but most people say it just gets gummy.
Pastels, watercolor pencils, and sealant definitely will do a fine job at face-ups. Admittedly, I'm not a pro, but that's what I use for my faceups, and I am quite happy with the results.