[Kie99]

That page doesn't say anything about EMP. EMP is generated by the atmosphere around the blast, not the blast itself. In space, I don't think you'll get any EMP.

Supercompressed air in the warhead which expands a fraction of a second before the explosives?

[General Battuta]

Maybe? If you purpose-built it.

[Mongoose]

But even then, the surface area of the released-air shockwave would swiftly dissipate via the inverse-square law as it moved away from the point of detonation.  At least how I see it, it wouldn't have nearly the range or destructive force as an atmospheric detonation, where the shock wave propagates through a uniform medium.

[Scotty]

EMP introduces an electrical current to the ships hull, overloading subsystems and scrambling those not disabled or damaged.   

[General Battuta]

EMP introduces an electrical current to the ships hull, overloading subsystems and scrambling those not disabled or damaged.   

If you're referring to specialist EMP weapons, those are possible in space, but you won't get an EMP off a regular nuke like a Harbinger or an antimatter weapon like a Helios (as you would in the atmosphere.)

[DIO]

As for radiation, space is filled with radiation anyway so any space ship would have defences against it.