On the OP, I don't see the benefits of decoy missiles outweighing the increase in UI complexity that would be required (see Missile Silo). I really like the simplicity of Nuke Silo, you build it, leave it to do its own thing, and later tell it to attack a location. Nuke is not primarily intended to be an endgame weapon, it is intended to create more targets of high importance (anti-nukes) within opponents bases. Having a nuke confers an advantage, but I don't want it to be any more of a slippery slope.
Would a decoy missile even be any good? What sort of stats would it need to be superior to 1000 metal of scouts? Remember that a decoy missile can only find one anti-nuke, does not reveal its location, and requires Silo-BP, which is much more valuable than regular buildpower. If nukes need buffing, why not buff them in a different way? This sounds like a suggestion to give energy structure an overcharge ability which increases their energy output but makes the energy only available for overdrive. Technically it is a buff, but it is a UI nightmare, and if I wanted to buff overdrive I would do take another approach.
I am also not in favour of multiple missile types, for similar reasons. The more interesting aspects of nuke play occur before impact, in the maneuvering required to sneak a nuke through. The details of the type of destruction caused by a nuke impact matter less than the fact that an impact occurred.
Big Skuttle seems like a good idea, but may be difficult to balance. What is the counterplay to launching this with a Newton ramp? If it only costs 3k-5k it sounds cheap and light enough to launch. Perhaps it needs to be on firm ground for some amount of time to activate its denotation.