So is it possible to be running mutiple households using the hearthfire DLC? By this I am asking can you have two or three houses owned by the PC and have a steward and housecarl for each? Also can you have kids for each home or is it like the wife where its only 1 at a time (two for kids) and you must have the wife at a single house. I also want to know can you have a guard dog for each house or only when kids accept it as a pet? Another thing is do carriage drivers and pets actively defend the house, or do they always sit back and watch?

Yes, you can have all three houses using the Hearthfire DLC, and a housecarl/steward in each.
However, you can only have one wife and two kids per game. (If you're on PC, there are mods that allow you to adopt multiple kids.)
Not sure about the dog - anyone?
I think the carriage drivers and pets are fairly passive (?) but the housecarls will actively defend the place.

I have Meeko at one house and a pet mud crab at the other.