Regarding the state of the killer's mind: I'm guessing 'not well'. Some talk of a 2 hour cooling off period which proves he was sane and rational. On the other hand, we have the time line...
Act 1: finds, and kills, ex-girlfriend.
Act 2: 2 hours pass.
Act 3: goes around school, trying to find the ex-girlfriend, shooting anyone that can't help him.
If he was sane, thinking straight, and acting in cold blood, why would he be trying to find his girlfriend?
Regarding the media and the blame game: it's not that surprising that news networks are looking for scapegoats. It makes them money, it appeases the masses, and besides which, televion and newspapers are losing money and customers to videogames every day.
Regarding the ensuing political debates: This massacre won't change the gun laws of the USA. Every right has its responsibility, every freedom has its cost. The cost of the freedom of gun ownership is incidents such as these, and the American citizenry has always been willing to accept that cost for their freedom.