If your looking at buying a camera, take a read of this : http://www.pmcgphotos.com/tutorials

It's a bit long but it will tell you everything you want to know about buying a DSLR.

If you are going to be shooting at night a lot, the two most important aspects of the camera are its noise levels at high ISOs and the maximum aperture of the lens you will be using. Shooting action at night is THE hardest situation to shoot motorsport or street drifting - Do your research and practice fuck loads and you'll be fine !