1) McKormick neon food coloring
2) till it's the right color
4) with a screwdriver
5) with a pipe clamp
6) nothing that I know of
Rudy you clearly don't bake or decorate with frosting much. lol The red and blue mix to be a much grayer purple than the newer neon dyes, at least in frosting, I would expect the same in the fluid.
I would say don't cut or puncture the stopper. The stopper seals the globe and the metal cap keeps the stopper in place, so there is the potential for the globe to not be sealed airtight if the stopper isn't intact.