Well, 2016 GT headlight units are the same as your Touring and Sport, why do you want to swap?
If you're talking about LED headlight units, that are included in the Tech Package. I believe you missed the chance to have them cheap at time when you're purchasing the CX-5 Touring. Each LED headlight assembly cost around $1,200 as a part!
I've seen people replacing their standard tail lights with LED tail light units which is simple plug-and-play. I'm pretty sure the front would be a lot more involved as the LED headlights also come with Adaptive Front Lighting System (AFS) which will turn your headlights left-and-right according to your steering wheel angle and up-and-down according to your load. You definitely need several sensors and some software updates to make AFS work.