Lorann makes both oils and flavorings. I would look at the flavorings, which are probably better suited for coming up with a cotton candy flavor. Oils don't mix especially well with alcohol (or water, and most vodka is 60% water) so you may end up with a slick of flavoring on top and not much flavor in the vodka. Their flavorings taste a lot like what is used in La Croix.
I don't have a specific suggestion on volume but you want to use a lot less than you think. I carb up a five gallon keg of water with these flavorings sometimes. I use between half to one teaspoon per five gallons of water depending on how aggressively I want the flavor. You probably want the vodka more aggressively flavored for mixing though. I would try sacrificing like four ounces to working up a recipe you like. Trying to do it one ounce at a time might be hard to measure out a small enough volume of flavoring unless you have some extremely small droppers. If you start small you can always add but never take away.