You'll need the Hella H4 conversion housings, available HERE, and sold individually. This lets you use normal H4 headlight bulbs instead of the stock sealed-beam units.

EDIT: THESE also look to be the same units for a much better price.

For the fog-lights, you don't need any sort of housing conversion, as they take 880-type bulbs, and you can buy HIDs in this size.

So all I did was to buy 2 sets of digital slim-ballast HID kits from HID-Direct for about $80 each. For the headlights, yes this was low-beam only. The install was pretty straightforward. The fog lights have room right above the lenses to mount the ballasts, and everything worked well.

The only kink was, as you alluded to, getting the fogs to work. Normally the fog lights are grounded through the high-beam filament. Apparently, this is the easiest way of having them turn off when the high beams turn on. Without a high-beam filament, no more fog lights. DO NOT just ground the high-beam wire! I tried this, and I fried my headlight switch unit.

$150 later, I picked up a pair of 50-ohm, 10-watt resistors from a local electronics repair shop. You will have to look around for these, as they are not common. They're huge. Ground the high beam wire through the resistor. These simulate the resistance of the high-beam filament, and have worked flawlessly so far. Just don't try to turn on your high beams for any length of time, because they will get really hot. And you'll have no light...

As far as bi-xenons go wrt fog lights, I'm not sure. It may work perfectly out of the box, since the kit actually uses the high beam wire. Then again, it may not.

I didn't have to change out any fuses, and haven't had any problem with the wiring. HIDs actually draw less current than stock during normal operation; they draw a little more during burn-in, but that doesn't last very long.

Lastly, a few words of wisdom having done it. If I did it over again, I would splurge and get the bi-xenon kit. It's $105, and a standard ballast as opposed to the digital slim one. But this will still fit inside the headlight bucket, and compared to the headlight assy, the weight difference is negligible. While low-beam only HIDs are fine 95% of the time, certain back roads and late-night highway situations make me wish I had high-beams. Plus, you can't flash your high beams to signal someone if you don't have any.

I'm glad I can help. For the color, I went with 5k. 4.5k is pure white, but you can't normally get this color. My 5k's are almost pure white, with a tinge of blue. Barely noticeable blue. It's perfect in my book; I got HIDs to light up the road, not to look ricey. The closer to 4.5k you get, the more light output. A friend of mine had 6k on his old car, and they looked good as well. Just a bit more bluish, as you could probably guess.

For the fog to match the headlights, just order them the same color. i.e. 5k, or 6k, or whatever. Then they will match. And yes, just single-beam for the foglights. The way HID-Direct does it, all their auctions are the same. Once you win, you specify bulb type and color. Makes things easy.