I watched the tralior like 3000 times, and it has a total of 3 snaps of parts of her costumes... There is a thread further down that has the pictures, it'll take 3 seconds to search for. (I'd bump it, but that would count as a double post)
Pretty much its a blue skirt, white shirt with really tiny sleeves, small blue tie, dark blue knee high socks and black school shoes. Kairis hair also looks more brown than the KH1 version, and is a bit longer. This could just be the lighting.
I see you bought/will buy the skirt. I painted mine, but I screwed it up a bit, and the waist band is WAY too but for me. If you do want to paint it, its a bit confusing because the two best shots of her skirt make them look completely different. I think it has 10 vertical white lines, two horizontal white lines, and the lines are outlined in blue.
I'll post photos of my Kairi one of these days, but it turned out pretty badly, I screwed up the painting soo much *sniff*
If I wanted to watch reality I wouldn't need a TV.