1. That's neither here nor there. We could decrease "stockpiles" by 1,000% and still have enough to bring about "doomsday." ALL nukes will go away AFTER doomsday, no earlier. ANY use of nukes can bring about doomsday. Even if we each only have 1, their use would bring about WWIII and no doubt more would be rebuilt and used as soon as they could in a large scale conflict like that.
The important part of the equation is how close people are to actually using nukes. That is the useful thing to track. People are constantly saying how the nuclear standoff is so dangerous, but don't seem to think about all the wars it has prevented from ever starting due to the mutual deterrence. A little education on strategy and past warfare goes a long way to helping to understand how important this has been. It would be nice if we could uninvent them, but what's done is done.
3. All very true, but has nothing to do with a doomsday clock. The doomsday clock carries with it an implicit "imminence" (hello! clock? minutes to midnight???) to the issues it is measuring. Climate change doesn't fit that at all. Furthermore, the constant hyperbole and "the sky is falling" coming from people who are fighting for climate change awareness is sounding ridiculous to reasonable people.
Instead of educating people on how CO2 affects the atmosphere, and how this could turn our planet uninhabitable over time if we don't curb our emissions quickly, people falsify reports to make up effects and data that supports their arguments, and talk like the world could end tomorrow. These things get disproven and seem absurd and they get called on the lies, and then perfectly reasonable people turn their noses at ALL the climate change evidence. It has gotten to the point where they want to change "skeptic" to "denier" so they have license to point and laugh at how stupid all the "deniers" are, when the deniers are being created by the very people that insist they are crazy.
STOP the hyperbole and the outright lying about climate change, and maybe people will start believing the truth, and we can all "row in the same direction" on solutions.