I am finishing my basement. It has the superior wall system which includes furring strips every 16 inches vertically, but no sill plate or top plate to support the drywall horizontally. Is this a problem? Specifically, should I try to install some sort of sill plate to provide support for the drywall or just leave it as is. And trust the molding to protect the bottom.

I've never had or seen a problem w/ drywalling that system. Use 1/2" drywall. If your really concerned about it, install firring strips every 12" perpendicular to the foundation firring strips. Still install the drywall horizontal. This way you'll support they drywall in the areas of your concern.