You simply need to connect any GPS Source that has NMEA out capability to the XPDR, its one wire and a ground
As to what capability it gives you...it allows anyone with an ADSB in capability to accurately see your position, height and registration so handy for traffic avoidance.
I have it enabled on my Trig and also use a a traffic detection unit that picks up ADSB as well as as Mode C/S and flarm
edit, you may be thinking oh well if my traffic detection thingy picks up mode S then the whole ADSB thing gives me nothing extra except registration which is not needed...this is not the case, the traffic units that pick up Mode C/S can only give a very vague position/altitude reading base on stuff like signal strngth or multilateration, whereas ADSB is giving out Data from GPS so accurate height, position and speed