Will it work with Kvatch Aftermath?
No. Just download and install the Cyrodiil Upgrade Resource Pack (CURP) - it is exactly as it is named, a resource pack. It makes no changes in-game by itself, it contains meshes, textures and sounds used by the mods created by the same author.
Dragon Captions Resource Pack (DCRP) is being replaced with the County Sutch Reborn Master (CSRM) resource pack. The DCRP is an old version of CURP, which many Dragon Captions mods made use of. The CURP was supposed to maintain backwards-compatibility with Dragon Captions mods, but it does not, as some critical records were removed from the CURP ESM. For this reason, Dragon Captions are moving onto the CSRM instead, totally independent of DCRP and CURP.
The mods created by the modder who tends to be referred to as "he who shall remain nameless" (or similar), and the modder himself, are not topics typically allowed to be discussed here on Beth forums, as usually any thread which comments on him or his mods leads to a bit of negativity towards the mod author. Reasons for such negativity are also not allowed to be discussed here on the forums.
So download the CURP to play Kvatch Aftermath, and
yes v7.3 is the final version, however the mod author did also create Kvatch Rising, which he considers a superior Kvatch mod.
EDIT
7.8 is the final Kvatch Aftermath release. It's been so long since I had to touch the mod, I forgot.