1. Perhaps they do. I honestly wouldn't know where to find illegal drugs. I'd be limited to going to Colorado and I suppose now Illinois (where they are legal anyway). That said, drugs and guns are different problems and have different (albeit sometimes overlapping) audiences.
2. Definitional problems with "open border" policy. Don't know which brand you are talking about. Can't really say how it affects gun control.
3. As always. the question is whether they've done better than they would have without gun control laws. Chicago will always have more murders than French Lick Indiana. But they might have had even more without gun control laws.
4., 5. Requires a definition. I would assume every poster that was driving a car today broke some laws. I would assume that even convicted murderers go days at a time without committing a crime.
6. Is that the proposal that is being put forth here? Making all guns illegal? Perhaps I am not the right person for this questionnaire.
7. No. They'll just be less empowered to kill.
8 You could benchmark by other countries. But here is my gut instinct. The number of crimes thwarted by use of a gun by a would-be victim is negligible.