I am sorry to learn of your troubles. What a pain. Regarding dogs, any dog will do. All you need is something that is alert and makes noise. Two are better than one. They keep each other company and usually develop patterns where they work almost as a team--one will watch and then the other.
Anyway, regarding the spray, pepper spray, if legal where you live, is the way to go. Mace does not have enough "stopping power" and neither do the stun guns/tasers if the perp is on drugs. Remember, stun guns have to be held in contact for a few seconds to be effective, which makes them less desirable in many cases.
Finally, regarding guns, although they are an option, they are only so if everyone in the house is trained. The way our goofy legal system works, using a gun can get you into more trouble than hitting them with a bat, which is also quite effective.
:saw: