Questions about Boston that really should be asked

Like everyone else with a TV or WiFi, I was glued to the news on Friday as Boston was shut down to hunt for the remaining suspect of the Boston Marathon bombing. It was an operation peerless in scope and precedent, and I had several questions that went unaddressed as the newscasters and Tweeters updated the world on the progress of the investigation.

• Is this a law enforcement matter, a national security issue, or some new combination of the two?
• Was this a dramatic overreaction: I know that it was believed that the individual (going unnamed because I cannot remember his name for the life of me) was wearing a suicide bomber vest and armed and heavily dangerous, but this was still one individual. Shutting down an entire city to look for one person strikes me heavily as overkill.
• Would the involvement of military personnel be a violation of posse comitatus, given that state and local government was completely functional, and this was looking for one individual and not a systemic or organized attack against the government by a larger force?
• Despite the obvious loss of life during the Boston Marathon bombings, did the (and this is going to sound patronizing and possibly insulting, and I beg your forgiveness) minor economically, politically and militarily marathon really justify such an extreme response the same way 9/11 did?
• If not, what would justify such an extreme measure? Assassination of the president? Destruction of an important target (and if so, what would that be) for the government of the United States? Given the militarization of the police forces of the United States post-9/11, will this establish a precedent for similar manhunts for comparatively minor offences?

No, I don't presume to have any answers, if any objective answers exist to these questions. I am a little concerned that MURIKAN-style hoo-rah patriotism is drowning out desperately needed questions that must be asked.

Oh, and CISPA passed on the day of the manhunt. That too.