If you want the newest set then buy in now as it is a limited edition and it may not be a available at the show.
I'm not sure if they will take the additives to the show because as you can imagine the can't take everything. If they do the ones is recommended you get first are the effects, so Pink Gold Sparkle, Green Gold Sparkle, Violet Pearl, and Spectrum shimmer. These will change the look of whatever colour you use and I think they are the easiest to use to start with. I've recently rediscovered my additives, they'd just been sat in a drawer unused for months but I'm now loving them and so are my clients. They are fun to completely change a colour, for fades or over cream puff for different designs and effects xx