The air handler is suspended horizontally from floor rafters in the crawlspace. Heat pump is a year and a half old and we haven't had any problems with it. The question is, the handler has a metal "floor" (the sheet facing the ground) and it gets cold. Now, I don't remember much science, but I do remember that if cold air and warm air meet, precipitation can occur, especially in the humid deep South. I don't think there's a leak any place, just eighty or so droplets along the face of the metal plate.

Should that have some insulation around it? We run a fan to circulate the air and are installing individual vent fans. Will that work, or should be do something else?

The air handler is insulated. It should not condense any moisture on the outside. If this is occuring you have a spillage of condensate from the pan on the interior coil of the unit getting the insulation wet. This will cause the temp of the cabinet to cool to a point that condensate will form on outside from exterior attic humidity.

Remove the panels that access the coil and check to see that this is not occuring. If so you may need to clean the AC coil and or replace the filter. Both being dirty or using one of those high efficency after market filters will cause water to over flow and back up into the air handler and cause the condition your seeing.