The skirts are the same as far as im aware. They are not added side skirts they are actually part of the car, like metal if you get what i mean. You cannot buy GTi side skirts from VW they only come with the cars.
As for the lights, i heard that you need a few other parts for the conversion other then just the light units themselfs, could be very expensive. £140 for each light then other parts, from VW. Not worth the money in my opinion.
If had was going to spend £400 on my car, id choose collies over lights anyday. I got full new "xenon bulbs" and replaced all my orange bulbs with clear ones. It looks really clean now.
Thats my opinion only though,
Phill.