Why I say confirmed our launch is there have been at least one close call on each side. One I remember the details of one was the USSR Officer in charge, Stanislav Petrov, over-rode the information from the radar and 40 years ago, on 26 September 1983, he saved from potential nuclear disaster.
When discussing this with some peers the consensus was that the would have to sound the alarm. Especially now, since it is unlikely a first strike would take out all cities [count on Russian duds], so the survivors would blame the bunker buddies (the higher people, ala Dr Strangelove)
who has authority to sound the Civil Defense system? who has the authority to confirm launches and who has authority to say 'our' launch? the government of your region with an ICBM... that is the answer to your first three.
The question is why do you think they wouldn't tell you about the launch counter-launch, when even one person escaping a blast zone would be better than none?
I must be missing some context because I have absolutely no idea what you're on about.
Who wouldn't tell who what and why does that matter?
you might not be up to this level of problem. come back two years after studying the psychology of panic
getting even one person out of the blast zone would be worth something.