[@Regitnui]

1) The Island is capable of sensing things throughout the city. Unless, of course, he was secretly hiding in that church. But if not, he must possess the ability to extend his senses through the matter he controls. So he should be able to track down the Kryptonites with relative ease. Just find the people with assault-rifle shaped matter in their houses.

2) What does killing innocents have to do with it? He's a High. Specifically the High Island. He can just to each of the individual members what he's currently doing to Guilt if that satisfies his conscience. Put em in a box underground. Creating air should be easy for him, and it's not like they can escape or avoid it.