So far I've found that if I have a white subject I need to slightly underexpose: 1/3 or 2/3 of a stop is generally enough to prevent burn out and any loss of detail. To compensate I then brighten the image in Photoshop: for the two shots above I used curves to boost the low and midtones. This technique seems to work well in that it brightens the image but doesn't loose detail from the whites. Remember these are NEFs, though, so I had more dynamic range to play with than I'd get with JPEGs.
On the subject of white balance you're best off using the manual modes or preset mode. If you're shooting NEFs then it doesn't matter so much since you can correct things using the Nikon View plug-in.
Since you've got plenty of time before the wedding see if you can find some subjects to experiment on. If you set the camera up to show highlights in playback mode (see pages 115 and 134 in the manual) and check your shots immediately after taking them then you should quickly get a feel for what works.