A conventional explosion is the rapid chemical conversion of an explosive to heat and gas creating a lot of pressure. In an open environment the pressure decreases at the rate of 1/radius^3, very quickly in other words.
A nuclear explosion is the rapid conversion of mass to heat and radiation, Apart from heating and expanding the air around the explosion no other pressure is created. This means a nuclear explosion is confined to a fairly small area, similar in effect to a lightening strike. Except for a direct hit a nuclear explosion is not significant and generally weaker than a conventional bomb.
Our masters know the truth behind nuclear weapons and use the threat of nuclear war to cow everyone into submission. They fear the masses realizing that there is nothing to fear.
From my understanding, the geometry / fabrication method of the implosion devices is what is kept top secret about the bomb. It has to be done in such a way as to create a roughly spherically symmetric force inwards since any imbalance would cause the material to just blow out to one side. Of course that would be the story told if they were lying about having an operational nuke.
Yes, the timing of a nuclear explosion has to be insanely accurate. What I have been told is that they use neutron reflectors to make the timing of the explosion more time tolerant and even out the reaction (there is a random element to it) which dramatically increases the yield.
It is the design of the reflectors that is the big secret, along with the secret that yield doesn't equate to explosive force.