People do work about all of them. How sucessfully - the war will demonstrate. But even bad our counter-force strike is better (for us) than the first strike of Americans.
No, they can't. Russia is big and 40-400 warheads will hurt it, but definitely not "destroy". What is even more important... If you, even after our counter-force strike (after which you have no any chance to "win" the war) still determined to attack Russia, and if you are going to attack Russia immediately (refusing Russian suggestion about two days humanitarian pause to evacuate at least children from the cities) - then you are definitely irrational, and it was good idea to kill you before you tried to kill us.
If you believe that your SSBNs are really invulnerable in the ocean (its not true, of course), and their nukes are absolutely devastating, its quite rational to accept himanitarian pause and evacuate your children.