Touch osc will turn your ipad into a midi controller, like the x1, so you'd plug it in and use it to control the software. Traktor dj is it's own dj software, and won't work with the Traktor running on your laptop (I really think you need to get the idea of running traktor dj on ipad alongside Traktor on your laptop out of your head, at least for now.)
If you're not using another controller/mixer with a built in soundcard, you'll need the Audio 2.