One thing I have noticed that 40k ships don't do really well, is the whole 'missile spam' thing, with missiles launching from all over the ship and then self targeting and accelerating at an enemy ship in any direction. At best, the ships did things like big torpedoes and, if you were the right xenos or you were humans way back when, those torpedoes could maybe do a bit of course correction. Presumably, the Tau tried this sort of thing and it didn't work at Void Ship scales, but maybe it was made to work well in the DAoT by humans? So what would a DAoT, archeotech macrobattery that launches a whole huge host of missiles, which can poooosssssibly be loaded with nukes (good against targets without void shields, or with the void shields taken down...) with autoloaders and a big munitorium and a dedicated manufactorum for making more of the things actually be statted like, as a Missle Battery or a Missile Battery Broadside? Any ideas?

As for trying it, there already is a component which does this, the Jovian Missile Battery, notable for noy being a broadside but still sporting a strength of 5. Downside is that there are so many missiles to load it can only fire every other round. Fit a lot of those on a small ship and you've got incredible burst damage if you can manage to hit.

Also, Tau torpedoes aren't really torpedoes as the Imperium knows torpedoes. Instead, they're a huge amount of smaller, vox-linked warheads with an innate target-seeking capability. Their guidance isn't perfect, however, which is why they have a tendency to crash into each other and reduce the salvo strength, at least in BFG.

Yeah, the Tau are really the king of the Micro-missile methodology, both on the table-top (er planetside) and in space.