On house targeting:
There are lots of crimes where a particular place (with people in it) were targeted. Manson case comes to mind, but also most of EARONS's killings (he was looking for a certain kind of window, a certain known-to-him tract home lay-out, and THEN he started looking for victims as he stalked).
The Nightstalker was also a "target-the-house" killer. On the weekend he was caught, the entire LA area was alerted as to the type of window he had used to enter houses, which caused a crazy run to hardware stores to find a way to secure those windows. It was very scary. Nightstalker moved from neighborhood to neighborhood, chose mostly ranch style houses or first floors of apartments, with a particular kind of window. He did not care who was inside, he planned to kill them and eat their food, sometimes hanging out for hours in the house.
That being said, in these killings, it's hard to believe the perp didn't use further observations (the fact that people were home was telegraphed by the cars). He brought the weapons with an intent to kill, IMO. "The house" could mean "the house, its occupants and all its usual doings." If the perp had a strong objection to the particular party lifestyle of the house (and other houses), choosing this house rather than the frat house seems to have obvious reasons behind it.
Anyway, if a type of house is being targeted then anyone else in the same type of house is at risk.