As for the countermeasures, even the single decoy launchers, such as the 6x4 on the Type 054A, fires different countermeasures. We have already seen that in many pictures. There are at least two kinds of decoys being fired and I would assume that one is an active one, as meaning it contains an active jammer or radar emitting decoy, or a passive one which is chaff based. The passive or chaff based one could be tailored for different wavelengths, with the chaff cut to specific lengths, and the defense system choosing from a pallet. Which chaff it will choose will depend on the wavelength of the incoming missile's seeker. There is a possibility there might be anti-torpedo and smoke decoys as well.
The decoy launchers do not have their own separate type. They are referred to as Type 726-4, which is the fourth of the Type 726 system, which includes the 726-1 ESM, 726-2 ESM, 726-3 ECM and 726-5 ESM. This means the 726-4 DLS is integrated with the electronic warfare system. This means for example, the ESM would intercept the enemy seeker's radar, analyze it, copies it, so the active decoy when launched, emits a copy of the same signal to confuse the seeker. Or it will match the proper chaff length and fire the right chaff from the DLS. The threat signal can be sampled to the HHQ-10 missile to home in.
The one on the Type 052C/D is the 726-4 which is an 8x3 unit and there are two of these. The one on the Type 054A is the 726-4A, which is a 6x4 unit. I have no idea why they have to produce a 6x4 unit when the 8x3 unit does the same. Indeed, the Type 054 refit reverts back to the 8x3 unit. The 8x3 unit on the Type 055 is probably the same as the one on the 052C/D but given a casing to reduce its radar cross section. The 8x4 unit on the Type 055 is new, probably a 726-4X, with X being another letter. I do not know exactly what are the units on the Liaoning, Shandong and Hainan, and presumably they might either be 6x4 or 8x4 units.
I have no idea why the 055 has both an 8x3 and 8x4, and why not just two 8x3 or two 8x4.
