Generally what should the tension be for spokes in wheels built up from scratch? For the front wheel? Should the tension be different for drive-side/non-drive-side spokes in the rear? Should tension run differently for different cycling applications E.G. mtb, cyclocross, pavement, touring, etc...
The rim manufacturer should have this information. It depends a lot on the number of spokes, if the holes have eyelets (metal grommets) and the material of the rim. Lower spoke count wheels need more tension. Generally eyeleted wheels can handle more tension.
As for symmetrical tension, that also depends. If the wheel is asymmetrical then your tension must be asymmetrical as well. Most multispeed rear wheels are asymmetrical. Many front disc (mtb, cyclocross, and even road wheels) are asymmetrical, although some are not. "Quick Spoke" for the iPhone is a spoke length calculator that also provides relative tension information.
TL;DR Check with the manufacturer.