1) Unless you're really trying, it's pretty difficult to burn down the neighborhood with a science kit. When using a cell phone jammer it's pretty hard not to affect all the people around you. That's kinda the point. Now, if you don't want cell phones used in some place that you own, then paint the walls with signal-blocking paint.

2) Have you tried to buy a chemical kit lately? They took out all the fun stuff years ago.