1) Changing gun laws won't stop these types of incidents, though the criteria as to what types of guns are allowed to be purchased might be considered.
2) Just because it is a disturbed white guy, it is as much an act of terrorism as it would be had the shooter been black and/or Muslim.
3) People will be ever more willing to trade in personal freedoms for greater public security...and our society will continue to change.
4) There are no easy answers in faith to tell people. I believe, for the record, that God had nothing to do with this, nor any sort of devil, though some fundamentalist friends whom I know would argue the latter to be the case.
You've got four different threads there. Which will this one be?
Love your enemies!