1. There is no 'best practice', it all depends on the image you want to create.
e.g. If you want to make a black and white photo, you convert to black and white before you change any other settings.
There isn't any fixed or rigid rule about the order of the settings you need to change. Just think about how you want your final output to look and then consider which settings should be adjusted. And finally you need to understand what each setting does to the image.
2. Adobe Camera Raw is not just about adjusting white balance. You can adjust the exposure, contrast, highlights, noise reduction, sharpness, etc.