The events and story in Paranormal Activity 4 (which is the sequel that uses the xbox 360 and Kinect took place in 2011 not 2006. If you watched the movie at all or read anything about it you would know because the boy who is supposed to be the baby Hunter is now about 5 years old meaning it takes place 5 years after the first and second movie. Gee but I still wonder if the riters were aware the the it didn't hit the shelves until 2010 and they placed a 2010 product in a 2011 based movie. Hm I wonder.
And to the thing about Katie dying, all the other endings were alternate. The original one and the one that all the sequels except #3 were based off was the one with her disappearing.