One option I heard discussed in an interview with Wesley Clark was that NATO would destroy the Russian navy base at Sebastapol and hit every Russian airbase near the border with Ukraine.1. sure it will. nukes end the world. Russia occupies this world too.
2. sure it will. wait and learn.
3. false. Ukraine is presently killing everything sent it's way. tedious and costly. but by every measure Russia is getting its ass kicked. it literally sends prisoners as fodder/to slaughter.
4. false. see #1
let russia detonate one and affect the west and it will find out.
That would be with conventional weapons, not nukes. Cruise missles and drones could do the job on the Baltic fleet. B2 bombers and F22 fighters could destroy the Russian airforce and airbases being used to attack Ukraine.
Obviously, if Putin chose to use a nuclear weapon on a member of Nato, all bets are off.