In LR4...sharpen before or after noise reduction?

The order of operation doesn't matter; since LR is a parametric editor it will figure out the logical order of operation for itself.  In any event, you should be using the masking slider in the Sharpening panel so that only edges are selected when doing Capture Sharpening and this will eliminate sharpening most of the noise present.

Zoom to 100 percent view, Hold down the ALT key and adjust the Masking slider

See this article; it was written when Lightroom v1.1 was released but the information on sharpening is still relevant:  http://lightroom-news.com/lightroom-11-update/sharpening/