Is it feasible to think in terms of designing a missile to take down an impeller wedge, or to damage nodes in a wedge through interference with the wedge? The original proposal, I believe, was for a missile which would be "bomb- pumped" (although I'm not sure exactly how that was supposed to work) to generate a brief, intense spike of gravitic energy which wouyld knock down the wedge or at least cause sufficient interference with it to damage or burn out individual nodes. Another proposal -- forgive me, but you did ask -- was to come up with a missile which would be able to knock out sidewalls, whether it could affect the wedge or not. I believe, err, a variant of the Unmentionable Weapon was involved in the sidewall killer, although it may actually have been a variant of the "bomb-pumped" (or equivalent) approach. Also, the "Crippler" has been adduced in support of the belief that a wedge can, indeed be knocked down.
Oh My God, not again!
I'm beginning to think that I need holy water and a wooden stake to deal with this abortion of a concept, too. And no one can blame me for this one, the way that I suppose in some ways they can for the grav lance.
Let me put this very simply: to take down an impeller wedge through a brute application of force requires an impeller wedge at least as powerful as the wedge you are trying to destroy. The more powerful wedge, always destroys the weaker wedge, and the more powerful wedge's generating nodes take no damage in the process. The infamous "Crippler" never damaged the nodes themselves, nor did it "smash" the wedge. It induced a power overload which took out engine room components upstream from the nodes, and note that even against a merchant ship wedge (which is far weaker and more vulnerable, ship size-for-ship size), it's effect was easily compensated for by simply installing circuit breakers.
There is no way to "bomb pump" (or the equivalent) the impeller wedge of a missile, or even a smaller starship, to allow it to overpower the wedge of a larger vessel. Ain't gonna happen. You could build a starship with over-powered nodes, which is basically what the Peeps did with the Mars-class, but even so, you would not be able to shoehorn anything capable of taking out, say, a dreadnought's wedge into anything smaller than a battleship-sized "missile." And the grav lance technology would be totally useless for enhancing the effect.
When the impeller wedges of two impeller-drive vessels come into contact, wedge interference causes the nodes of the weaker vessel (or of both vessels, if the wedges are quite close together in the size and strength) to vaporize. The portion of the hull in which the nodes are mounted goes with it, and the capacitor rings associated with the nodes arc over and release all of their stored energy in the process. And if you think about the power levels routinely involved in Honorverse technology, I think you can see why this particular form of collision has a tendency to totally destroyed its victim at least as spectacularly as a breached fusion bottle.
The sole exception to the above occurs when one ship's impeller wedge is fully established, and the other ship's impeller wedge is not. There is a time period during the powering-up process for a wedge during which the wedge is actually "up" but not yet established at full power. In effect, there is an area around the ship in question in which there is a powerfully stressed gravity band which is readily observable and highly destructive to any material object in its area of effect, but which is vastly weaker than an all-up impeller wedge. You might think of it as the first stage of a multi-stage activation process. This field's existence is readily detectable, but a smaller vessel with a fully established impeller wedge could, if it entered the area of the "first-stage" field, knock out the impeller nodes producing it. Because the power levels involved are still orders of magnitude lower then those involved when the nodes go fully active and the wedge goes to full strength, the destruction is far less spectacular. Thus Honor was able to take out the nodes of the courier vessel in Basilisk without completely destroying the ship. And the fact that the courier boat's "first-stage" field had the same dimensions as its full- powered wedge would have had is why she was able to come close enough to take the field down without physically contacting the courier boat itself. Had the positions of the two vessels been reversed -- that is, had Fearless been bringing up her wedge and the skipper of the Peep courier boat had been able to maneuver his vessel, with fully established wedge, through the cruiser's "first- stage" field -- Fearless would have suffered effectively the same damage that the courier boat did.
Note that smaller and weaker impeller wedges come up faster than larger and stronger ones. This means that the courier boat's window vulnerability was actually narrower than Fearless' would have been. This also applies to missile impeller wedges, where the differences in the fundamental technology (see the answers to your second question above) also come into play. If it didn't, an impeller-drive missile would take so long to bring its wedge up from "standby" that it would be totally useless as a weapon system.