You can alway ground yourself when petting them lol, it does sound to dry, I have had the indoor vent and it works well, though the room it is in if it is small enough can be like a sauna, a fan and open door will help with that. (unless you want to have a sauna that is) most furnaces have a humidity thing on it, you may want to make sure if you do that it is working, Having one of those table top water fountains helps though the cats will think that you put it in for them, just keep an eye on it so that it doesn't go dry, it isn't good for the pump, Plants also help with the humidity in the house and help keep it balanced, you will find the dryer the house the faster they will dry out, okay I am done rambling.