No, don't use those. They won't hold anything in place very well, and they will scratch your paint. Go to www.mcmaster.com and seach for "P clamp". You will find a wide assortment of cushioned clamps that will hold on much more tightly, and won't damage your bike's finish. They'll look more professional, too.


As for isolation of the substrate (actually just called a Slug), just make sure that it isn't connected to the +ve or -ve poles on the LED in any way. It's best to use an electrically isolating thermal pad (like what you'd put between a big transistor and a heatsink), but if you just connect it to the heatsink directly it should be ok...