It does sound like something else is up in this case. I would guess one occupant in the house was the target and the others were killed to remove witnesses. Very sad.
As for security, the linked lighting is a good idea. People trying to not be seen don't like surprises. Loud noises(barking dogs, explosions ect), bright and or flashing lights suddenly put into action will all serve to change their plans. A loud noise not normally heard at night in your area such as a blank round/gunshot/squib going off outside the house will be a very unwelcome surprise for a prowler and will also get your neighbors wondering what is happening.
I like the autodialing alarm systems. Monitored security is Ok I guess but as mentioned, they are just going to dial 911 after they try and confirm that it is indeed a genuine alarm.
Buckshot and shotguns are great, unless you have other family in the house or neighbors in close proximity. A .32 roundball can kill at a considerable distance. If this is truely a defense firearm for a defense scenario then it will be fired at close range. They will be close enough to hear you pump it, you will be close enough to see clearly who you are unloading on. At close range(less than 25') a lighter shot load, say #4-#6, will be just as effective as the shot patern will not have spread out. The mass of shot will be impacting the target as a close group and will deliver devistating energy, just as a 00 buck load would do at these short ranges. But if you should miss, which is not at all uncommon in a stress-fire situation, that mass of shot will spread and loose it's effectiveness quickly, particularly if it contacts anything along the way(window, wall, screen door ect). The larger balls in buckshot can pass thru lightweight obstacles and still retain quite a bit of energy. The smaller shot is a safer option in close quarters.
From a legal standpoint, if you should have to defend your actions in a courtroom afterward, you do not appear to have deliberatly used a particularly human lethal round(with the specific intent to kill) on your attacker.
The only person guaranteed to be there when you are in trouble is YOU. Plan accordingly.