Got-Busa,
I spoke with Ryan at XenonKing and I believe the correct bulb for the Busa (what I installed in my 05LE anyway) is an H7. The price for the low beam only (high beam worthless in my opinion) was $162 shipped to my door. It includes the bulb, ballast, and ignitor. It also comes with a few wire ties and a square of double sided tape. I believe ICEMANN has an installation write up somewhere and if you can't find it I will email it to you. You don't have to worry about melting anything cuz the xenon bulb isn't as hot as your stock bulb. The xenon consumes less power as well (35w as opposed to 65w stock.) Other than the tools to get the fairing off (4mm and 5mm allen wrenches,) you'll need an 8mm socket for the mirrors, 10mm socket to remove instrument cluster (makes it easier to adjust aim of lights and very easy to remove,) a pair of wire cutters/strippers that has a 16 guage option for the headlight wires, some electrical tape, and last but not least patience.
It's not that difficult to install and you become more familiar with your girlfriend (Busa that is.) As for your last question, I got the 5000K McCulloch kit. I believe the difference in number has to do with the color of the light. I don't even use my high beam now. Even when it's properly adjusted I can see the high beam hit the road about a third of the distance that the xenon low beam does. Words and even pics can't describe the difference from stock. If you have any more questions post away.
Later